# Mad River Adventure 16" - How to repair scratches on bottom



## danjaquino (Jun 2, 2005)

Hello All,
I just purchased a mad river 16 foot canoe this past summer and after a couple of trips, I've aquired some nasty scracthes in the bottom of my boat. The boat is high-density polyethylene I believe and I'm not sure the best way to repair those scratches without causing further damage. I'd appeciate if someone would share any information that may have.
-thanks,
dan


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## sauguy (Apr 8, 2004)

don't waste your time with them. as long as you float streams and rivers you will get them. it would be a constant job, trying to fix them. actually, don't know how you would anyway. all of us have them.


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## Wow (May 17, 2010)

Dan, If you look down a few threads , you'll see "Protecting Your Kayak". It seems that some people are resigned to acquiring damage and doing nothing about it. I'm not hardwired that way. The good news is that polyethylene is pliable when heated and very patchable. Check out yu-tube, surf "kayak repair" and "canoe Repair". There's good instructional videos. I'm interested in preventing damage to the heavy wear points for and aft. I found a tape distributer that carries an ultra high molecular weight, polyethylene tape. It comes in 5, 10, and 20 mills thick. It claims to have more abrasion resistance than steel. I called the company and requested samples to try it out. It's transparent, so color isn't an issue. I'll let you know if it's any good. -Tim


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## mishmosh (Jul 22, 2007)

I'm with sauguy. Trying to deal with scratches on a kayak is like akin to trying to keep your golf clubs scratch free. It'll have some scratches. Deal with it when it becomes a problem. Of course, I'm wondering how nasty is "nasty"? Got pics?


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## danjaquino (Jun 2, 2005)

Thanks for the responses guys. Well, they are not that bad. but, I figured, if I did a little repair once a year during the winter when it is boring as hell, it wouldn't be too big of a chore. I'll check out youtube, I have heard of guys heating the plastic and fixing it that way, but I do not want to ruin the boat. thanks guys!!


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## Rybo (Jul 23, 2009)

I like your thinking Dan. No harm in some time spent in the garage, getting excited for the coming spring. I'll be doing the same, whether it's necessary or not. Right after I get done categorizing my worms by light reflectivity to the .0001.


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## Sleprock (Dec 16, 2005)

a fiberglass kit in automotive for
$20.it will stick to that plastic for a while 

my canoe leaks but the hole goes from side to side not front to back, the scraches i dont think are leaking putting 3rd patch on soon.


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## streamstalker (Jul 8, 2005)

I'm not into fixing anything that does not leak, but maybe you can just fill in the scratches with an epoxy compound. It worked well on a yak of mine made of Trylene after it developed some small cracks.


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## Wow (May 17, 2010)

I agree with you Streamstalker, you can't worry about cosmetic scratches on your craft. What is, worth some preventative measures, is the areas on the keel, just below the rockers, fore and aft. If you're going to develop a hole, thats where it gonna be.


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## Bubbagon (Mar 8, 2010)

streamstalker said:


> I'm not into fixing anything that does not leak,


We have a winner!! If it aint broke, don't fix it. That's like Dad rule number 3.

Between myself and 3 of my buddies, I believe we have over 40 kayaks and canoes....all of them some poly-based plastic. Some are newer, some are well over 15-20 years old.
I can't think of an instance in which a repair was ever needed from scratches, dents, gouges, etc...that occurred on the river. And ALL of those boats get used on rivers...in a hard way. Lots of dragging from place to place, lots of rocks hit, etc...

I equate filling scratches on the bottom of a canoe to trying to keep the bottoms of your new sneakers clean. Sooner or later, you're going to have to let go of that idea or you'll drive yourself crazy.


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## Wow (May 17, 2010)

I get it, Bubba. All hail! King Bubba the Grand Wahzoo of Yakademia, Poobah of the Paddle, Wazir of the Water. If my friends and I averaged 10 yaks or canoes each, thered be little need of maintenance. No "one" craft takes all the abuse. Do you drive a vehicle? Do you wax it? Do you change the oil? Or do you have 10 parked in the driveway? I have 10 reels, but I still clean and lube them during the season. I love my yak. I wash her gently, til shes squeaky clean. I check her hardware for wear and tear. I even, God forbid, protect her from nasty abrasive damage. I do the same for my canoe. Thats the way I roll. Im sure theyll last me a long, long, long time. Kayak dealers everywhere, be damned! Find suckers for your latest, overpriced models, elsewhere! .Gotta roll now, got a date with a lazy river.  Later yall!


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## Bubbagon (Mar 8, 2010)

Wow said:


> I get it, Bubba&#8230;. All hail! &#8220;King Bubba&#8221; the Grand Wahzoo of Yakademia, Poobah of the Paddle, Wazir of the Water. If my friends and I averaged 10 yaks or canoes each, there&#8217;d be little need of maintenance. No "one" craft takes all the abuse. Do you drive a vehicle? Do you wax it? Do you change the oil? &#8230;Or do you have 10 parked in the driveway? I have 10 reels, but I still clean and lube them during the season. I love my yak. I wash her gently, &#8216;til she&#8217;s squeaky clean. I check her hardware for wear and tear. I even, God forbid, protect her from nasty abrasive damage. I do the same for my canoe. That&#8217;s the way I roll. I&#8217;m sure they&#8217;ll last me a long, long, long time. Kayak dealers everywhere, be damned! Find suckers for your latest, overpriced models, elsewhere! &#8230;&#8230;.Gotta roll now, got a date with a lazy river. &#8212; Later y&#8217;all!


Sorry we disagree on this Wow. And quite the mature response.

And yes, ONE craft takes all that abuse. When I paddle, I paddle the same yak I've been paddling for over 10 years. I drag it to the river, from the river, over rocks, I've dropped it off the top of my truck a few dozen times.
It has crazy amounts of scratches. It has never thought about leaking and I can't imagine it will in the rest of my paddling lifetime.

I own several yaks. I also have several kids. But my primary boat sees at least 80-100 days a year on the river.

I can only speak from experience. And my experience has never seen a boat that needed repair from anything from normal wear and tear.
I also know probably another 60 guys who own yaks and use them hard. I frequent several yakking and fishing websites. And I've just never heard of a guy who NEEDED to repair scratches on his yak.
I've heard of guys dragging them behind their cars on accident, melting them in fires, wrapping them around trees on the New River, and maybe even the occasional interaction with some submerged rebar. THAT kind of stuff needs repairs.
I thnk one of the absolute best reasons to own a kayak is that it is NOTHING like owning a car, or any other motorized vehicle. They require no maintenance. They are literally a piece of plastic.
That's about the most absurd analogy I've ever read.


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## Wow (May 17, 2010)

I'm not sorry we disagree. It would be one God awful world, if everyone had the same opinion. Im happy for you, that you havent encountered any serious wear on your yak, IN YOUR EXPERIENCE. In my experience, I have. I yak often and hard. Several launch areas I have had to use, eat kayaks and canoes for lunch, dinner and a midnight snack. Some boat launches scrape the plastic like a wood planer, Putting in and taking out. This isnt anecdotal evidence, this is real, in your face, damage. Im not waiting for it to wear through, before I address the issue. I have met hundreds of kayak and canoe owners lakeside, at rallys, races, Guinness record events, as well as outfitters in Michigan, Ontario, and Ohio. All spanning 35 years. We often talk about maintenance and upkeep. Ive learned a lot from these people and Ill never stop learning. Its absurd to believe that plastic is indestructible in any application, let alone paddlecraft, as you said, Its a piece of plastic. Often a piece of plastic, your life depends on. So, keeping your plastic, fiberglass, royalex or Kevlar in good shape is a wise, if not life saving, endeavor, If not for you, than for those who also use your crafts. There are many remedies out there, some better than others, and more to come. Those who choose to ignore them can live with the consequences. People ask for some advice on maintenance, and your response is If it aint broke, dont fix it ?.. Really!... Thats what they said about the Hindenburg, The space shuttle, and the Deep water horizon. Hows that analogy?


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## Bubbagon (Mar 8, 2010)

A bit of a drama queen aren't we?
Launches that eat a yak's lunch and a midnight snack... the Hindenburg, the Space Shuttle...my life depends on this piece of plastic...LOL!!!
You're funny, dude. He asked a question about friggin' SCRATCHES on the bottom of his canoe. Again, it's a molded piece of plastic, not a trillion dollar rocket. 
And I've yet to see anyone's yak fail to the point where their life was in jeopardy...or at least not from excessive scratching and abrasions. LOL!!

Maybe in your case you should toss that baby up on your shoulder every so often if these places are so utterly vicious, I dunno, maybe a kayak cart. I mean how many times does this happen before you figure out to hike that baby up and stop dragging?
If you're so anal about your gear, how could this possibly be happening? Even I pick my yak up when I'm dragging over concrete or pavement.
I pick it up, carry it to the water and place it in. No "damage".
If you don't want to scratch your yak OUT of the water, that's pretty simple. Now how these "boat launches scrape the plastic like a wood planer, Putting in and taking out" once you get to the water, is simply beyond my understanding.



On the original question on the scratches, if they look like they were made with a sharp nail drug down your canoe. I wouldn't worry about it. If they look like they were made with a sharp railroad tie and a chisel, then you might want to jerk around with it.
There's a HUGE difference between scratches and "damage" as Wow keeps saying. Scratches are cosmetic.


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## JamesT (Jul 22, 2005)

"polyethylene with more abrasion resistance than steel" bwahaha


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## Wow (May 17, 2010)

JamesT said:


> "polyethylene with more abrasion resistance than steel" bwahaha


Yea JT, It sounds far fetched. But I figured, if there was a solution out there, it would come from manufacturing and engineering, and not from the yak industry. They furnish samples upon request, for testing, so I've got nothing to loose. So I'm gonna try some on the indestructible plastic, my yak is made of, to prevent the imaginary wear spots, that cause the imaginary hole, that let in imaginary water, that i'll imagine I'm bailing,if I don't drown first. Check out the link below.--Tim--(love the fish GIF) ................ And talk about drama queens, your highness Bubba, what don't you understand about plastic wearing thin and fixing it before it wears through?!? ...............................FAMOUS LAST WORDS: Quote: If it ain't broke, don't fix it! LOL............... http://tapesolutionsinc.com/4x18yd-uhmw-t418.html


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## Bubbagon (Mar 8, 2010)

What don't you understand about cosmetic scratches? 
This isn't about protecting your for and aft from abuse, it's a question about what to do about scratches on the bottom of a canoe.

I know enough about epoxy repairs and plastic welding to know that one could do more damage than help if they messed up a little.
And I've never seen a kayak or canoe that gets used on rivers that didn't have a bunch of scratches on the bottom. Comes with the territory.

All this other stuff about how your life depends on that plastic, the Space Shuttle, etc...well, it has given me a few chuckles over the last few days.


Good luck, Dan. Hit up Critter and we'll get out on the water soon. We can all take a look at your scratches and see just how life threateneing they may be.


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## JamesT (Jul 22, 2005)

for shiggles

2.3 Tribology - The Study of Friction, Wear, and Lubrication 
The study of tribology is truly interdisciplinary and encompasses numerous fields of study. Some of these fields include: materials science and engineering, mechanical engineering, chemistry, physics, chemical engineering, geology, manufacturing engineering, and even biology. Because there are people with such varying backgrounds in this field, a single universally accepted categorization of wear theories and mechanisms does not exist. To make things even more confusing, many of the "accepted" mechanisms occur and interact simultaneously in a wear situation. One can argue that all are interrelated - however subtle the interrelationship may be. Fortunately there is general agreement that a single mechanism will often dominate and thus control the overall wear rate in a given tribosystem. The wear mechanisms/theories applicable to this research are as follows. Before outlining the different wear modes, however, the importance of tribo-surfaces is discussed since they apply to all types of wear mechanisms. 
2.3.1 Tribo-Surfaces 
Surface properties are very important and play a major role in determining wear behavior. After all, wear occurs at the surface. As wear progresses, the surface can change in such a way that a transition occurs in the friction and wear behavior. Some important features of the surface include its geometry and its mechanical, physical, and chemical properties.
Geometrical parameters include the macroscopic shape of the contacting surfaces, as well as the microscopic shape, amount, and distribution of the asperities. An asperity is simply a protruding part on the surface of the material -- a high point. Mechanical properties include macrohardness, microhardness, Young's modulus, shear strength, and fatigue properties. Microhardness is different than macrohardness since a material is often a composite with smaller distinct constituents which have varying hardnesses. Physical characteristics include crystal structure and associated lattice parameters, thermal conductivity, and the ability of a material to work harden. Chemical factors might include chemical composition of the surface or how clean one is able to make a surface. Miedema states "any two metals can be bonded strongly, provided that the initial surfaces are clean" [8]. These are just some examples. In addition, many of these depend on the chemical environment in which sliding occurs.
Initially two tribo-surfaces (disk and counterface in this research) are covered with layers of oxides, sulfides, and other solid compounds. On top of these compounds there are films of adsorbed gases and hydrocarbons. Without these surface layers, the mating surfaces could bond more strongly. Once sliding occurs, tangential motion at the interface disperses these contaminants at the contact points and cold welding can occur at these junctions. As sliding continues, these junctions are sheared and new junctions are formed. Wear debris is formed by this continuing adhesion and fracture of the mating surfaces. This is one example of a possible wear process.
The act of wearing is a dynamic process, that is, the system is constantly changing and the process of wear can change some of the factors mentioned above. While the surface parameters affect the wear behavior, wear can also affect the surface parameters. In a stable or steady state wear situation, the change in the surface properties is negligible as wear progresses. To properly design a stable tribosystem one needs to understand the interrelationships between friction and wear and their effects on the tribo-surface.
2.3.2 Stresses Involved in Tribotesting
The stresses a material is subjected to during a sliding test (or for that matter rolling or impact also) can be considered on a macroscopic level as well as a microscopic level. The "macrostresses" are related to the overall geometry of the contacting members. The overall geometry is sometimes referred to as the "apparent area of contact". The "microstresses" relate to the local geometry of the asperity contacts. These local contacts define the "real area of contact".
Considering the "macrosystem" of stresses, there are two general contact situations. An example of a conforming contact is a flat surface rubbing against another flat surface. An example of a nonconforming contact situation, is a sphere rubbing against a flat surface. For a conforming contact with normal forces only, the pressure distribution across the surface is uniform. The stress level is maximum on the surface. In a nonconforming contact situation, the stress level is not maximum on the surface. The Hertz contact theory predicts that the pressure is greatest in the middle of the contact and that the maximum shear stress is actually below the surface [9]. The distance below the surface has been estimated to be equal to one-third of the radius of the apparent contact area. Its value has been estimated to be approximately one-third of the maximum contact pressure [10]. So, in the case of a non-conforming contact situation, which is the case for this research (although it changes towards a conforming contact situation as the tribotest progresses), the maximum shear stresses are actually below the surface.
The "macrostress" system and "microstress" system are really just ways of thinking about stresses. In reality a given contact has elements of both of these theories. The pressure distribution associated with a macrosystem can affect the load distribution across the asperities. As mentioned earlier, for nonconforming contacts, asperities in the center of the contact region will be loaded more than asperities near the edges of the contact region. When the asperities are loaded elastically, the stress field for a given asperity is similar to that of a nonconforming contact area since asperities usually have curvature. When the asperities are loaded at higher loads which cause plastic deformation, the stress field for the asperity approaches that of a conforming contact area situation. It should also be noted that as wear occurs, the stresses involved in the contact, both macrostresses and microstresses, can change -- it is a very dynamic process. An example of this is that a contact which was originally nonconforming can become a conforming contact as wear progresses. That is the case for this research. 
2.3.3 Adhesive Wear 
This type of wear has also been termed "sliding wear". Though sliding wear has also been used as a more general term which includes adhesive wear as just one of many components involved. Before describing this wear mode, it should be made clear that just because material of opposing surfaces is found adhered to one another after a wear test does not necessarily imply that chemical adhesion has occurred and one cannot jump to the conclusion that adhesive wear was occurring. 
When two surfaces are mated to one another, actual contact only occurs at various isolated points (the asperities) called junctions. When the areas of all the junctions are summed, one obtains the real area of contact. On the other hand, the area of contact which one determines through geometrical considerations of the actual part on a macroscopic level is called the apparent area of contact. The real area of contact is usually much less than the apparent area -- sometimes a thousand or more times less [11]. Typically the real area is about 1% of the apparent area. The diameter of typical junctions has been estimated to range from 1 micrometer to 100 micrometers [12]. 
Considering only the real area of contact, it is the protruding asperities which will make contact with the opposing surface (and its protruding asperities). On an atomic level, because a force is being applied to push two surfaces together, bonding will occur somewhere in the junction if the two materials have compatible structures. The extent of cleanliness and other factors such as temperature and environment also play a role. This is due to the nature of atomic forces. 
Figure 1 shows the force versus distance between two surfaces [13] which is similar to the inter-atomic force vs. distance between two atoms [14]. Being in the trough signifies bonding and somewhere in any given junction there will be atoms which are in the trough. Thus there will almost always be some bonding between two unlubricated surfaces when an external force is applied. How much bonding occurs over a given junction depends on many things including the force applied, the compatibility of the crystal structures, material properties such as Young's modulus, how closely the two surfaces mate to one another on an atomic level and how clean the surfaces are. As two surfaces are properly cleaned the friction coefficient can become very large due to adhesion effects, sometimes even exceeding 100 [15]. This type of cleaning can involve sputtering in a vacuum chamber. 
If one considers two surfaces, each containing an infinite number of atoms being pressed together, statistics tells us that at some location in the interface of the two surfaces, the atoms of the opposing materials will be properly positioned and will lie in the trough of Figure 1. This creates a bond. As a tangential force is applied through sliding, the bond may break where it was formed. This does not lead to adhesive wear. If it breaks in the interior of either of the original surfaces though, adhesive wear has occurred. It will generally break in the softer of the two materials. 
Thinking about this on a more macroscopic level, the asperities form the junctions, and when a normal force (load) and tangential force (sliding) are applied, these asperities or junctions may deform plastically (bond breaking in the interior of either of the original surfaces -- generally the softer material), elastically (bond breaking in the junction, thus leaving the original materials unharmed), or some of each. In addition to the factors mentioned above, this also depends on the number of junctions and the size of the junctions. In most cases there is some amount of plastic deformation occurring at some of the junctions. This plastic deformation is extremely noteworthy because it is a significant dissipative process for friction in crystalline materials such as metals [16]. Plastic deformation is a very important way of storing energy and converting mechanical work to heat. 
Topography studies of most post-tested wear surfaces show that evidence of plastic deformation can usually be found somewhere locally on the tested surface. Longitudinal cross sections allow estimates of surface strain and strain profiles near the surface [17]. Strains exceeding 1000% develop quickly under the imposed compressive and shear stresses involved in sliding [18]. 
One of the earlier theories proposed gives a clear summary of the most familiar ideas about adhesive wear. It states that transfer occurs if the shear strength of the adhesive bond between two asperities is greater than that of the transferring material [19]. The preferred transfer direction is from the cohesively weaker material to the cohesively stronger material. Other geometrical factors are also important. For example, in a pin-on-disk situation, transfer generally occurs from the disk to the pin. As a consequence, the disk has a larger wear loss [20]. Lubrication is generally a good way to inhibit adhesive wear. 
2.3.4 Abrasive Wear 
There are three general abrasive wear situations, two of which are relevant to this research. In the first case, hard asperities from one surface get pressed into a softer surface. This type of abrasive wear is termed "two-body abrasive wear". Sanding, filing, and a rough metal surface sliding against a polymer are all examples of two-body abrasive wear. 
The other form of abrasive wear applicable to this research occurs when hard loose particles get trapped between the two surfaces and the forces between the two surfaces must be transferred through these loose particles. This is termed "three-body abrasion" and the particles may be generated by brittle fracture. Examples of this are when dirt containing hard particles gets trapped in the bearing of a mountain bicycle wheel hub or simply when hard wear debris gets trapped between two sliding surfaces. The third situation of abrasive wear (not applicable to this research) is the direct impingement of hard particles on a surface; it is termed erosion. 
Abrasive wear generally causes damage in a single action. The hard particles of one surface or particles which are entrapped between two surfaces cause a permanent change in the physical dimensions of the other surface on their first pass over it. The most important factors which govern abrasive wear are the number of hard protruding particles present, their shape, and their hardness. The wear which occurs can be deformation with no material loss or it can cause particle formation (material removal). Which of these occurs depends on the material properties of the abrading particles (either loose third-body particles or asperities on the opposing surface) as well as material properties of the abraded material. Sometimes when a material is only deformed and no material is lost (no weight change), the wear mechanism is termed plowing. Continued plowing, however, can eventually lead to wear debris. Rigney and Glaeser state that the repeated plowing of asperity contacts over a ductile mating surface can produce high dislocation densities. This brings about an eventual change in the microstructure which assumes a cellular pattern characteristic of heavily deformed metals. This structure presents many favorable sites for subsurface cracking and the eventual release of thin wear flakes [21]. 
Cutting or scratching has been used to describe when material is removed in an abrasive manner. The wear scars are different for the plowing and cutting modes of abrasive wear. Mulhearn and Samuels have shown that the angle which an abrading particle makes with an opposing surface can determine whether plowing or cutting occurs. This "critical rake angle" often determines the transition between cutting and plowing [22]. Most of the abrasive wear models include geometric asperity descriptions, so that wear rates turn out to be very dependent on the shape and apex angles of the abrasive particles moving along the surface. If a significant portion of contact events is of cutting type, abrasion is a form of wear which is relatively efficient [22]. Cutting type behavior depends on the mechanical properties, especially hardness, of the surface which is being worn since cutting requires indentation. The wear debris generated from cutting and plowing type events can differ considerably. 
Any wear situation can be thought of as being part of a spectrum with (micro)cutting at the left side (most effective) and less efficient wear mechanisms such as smooth sliding towards the right. In this representation, the overall abrasion processes are intermediate, with the most efficient ones towards the left (mostly cutting) and others further right (less cutting, smoother sliding) [23]. Abrasion is most effective when microcutting dominates. Microcutting occurs when hardness differences are sufficient and when local rake angles are appropriate. The debris particles generated are usually cutting chips with a composition basically identical to that of the abraded material [24]. Where a given situation falls depends on the factors mentioned in this section. Lubrication may have little effect on abrasive wear and in certain cases adding a lubricant may actually increase the wear rate [25]. 
2.3.5 Fatigue Wear 
Fatigue wear operates on the principle that as sliding, rolling, or impacting occurs repeatedly under the same operating conditions, material near the surface experiences cyclic stresses. These cyclic stresses initiate cracks in these near-surface regions. Once the cracks are formed, more cycling can cause crack growth and the cracks can link up with each other as well as with the surface. In doing so, a crack network is formed and loose debris is generated which can be removed from the surface by continued motion. The debris does not necessarily get removed though and can even act to transfer the load in a subsequent cycle (a "three-body" effect). The end result of this process is wear and thus the formation of a new surface. This new wear surface will experience the same cyclic stresses which led to its existence and the process is able to start over. 
Though a fatigue wear mechanism is more common in rolling and impact situations, it may also occur in sliding situations such as in this research. In rolling situations where fatigue wear is the dominant wear mechanism, the wear scar often clearly shows crack formation and crack growth. Under sliding conditions, however, the wear scar morphology does not show the cracks as clearly. The reason is that during sliding, adhesive and abrasive wear mechanisms often operate simultaneously with the fatigue wear mechanism. As a consequence of adhesion and abrasion, the wear scar cracking caused by fatigue is often more difficult to see since features characteristic of abrasion and adhesion are also present and tend to mask the features associated with pure fatigue. Another difference of the fatigue wear mechanism in sliding versus rolling or impact is that in sliding, the crack networks are not as coarse and thus smaller wear debris particles result during sliding. This is not true in all cases though. 
In fatigue wear there is often an initial period during which cracks are formed and propagate to the surface. However, no wear occurs, as there is no loss of material from the surface; no debris particles have yet been formed. This period during which cracking and plastic deformation are occurring, but there is no loss of material, is often referred to as the "incubation period". Once the incubation period is over, material loss occurs with the formation of loose debris particles. As mentioned earlier, the process repeats and the end result is a wear scar which keeps growing larger. 
A major difference between conventional fatigue and the fatigue wear mechanism model is that in conventional fatigue there may be a stress level below which fracture will not occur. In fatigue wear, however, at least on a macroscopic level of loading, there does not appear to be a stress below which wear particles will not be generated. With enough sliding, rolling, or impact, wear and loss of material will occur. Another difference is that conventional fatigue generally involves some amount of tensile loading. Fatigue wear, on the other hand, need not have tensile forces involved. In a conforming contact situation there are no true macroscopic tensile forces involved. A nonconforming contact situation may have tensile forces involved. An example of where there are tensile forces involved is at the trailing edge of a sphere (but on the opposing disk) in a sphere-on-disk apparatus. In this situation tensile forces are developed due to the Hertzian nature of the forces involved. 
A type of fatigue wear which also incorporates aspects of adhesion, abrasion, oxidative wear, and other types of wear is delamination. When cracking occurs near and parallel to the surface it is termed delamination wear. While direct delamination of debris flakes from the base material has been observed in certain systems, it is not the norm. Although tribologists such as Glaeser [26] and Blau [27] have observed direct delamination, Rigney points out that the evidence for direct delamination of base material to form flakes is very meager and unconvincing. "The experimental evidence provided for wear by simple delamination is not convincing" [28]. Rather, the delaminated flake debris is believed to originate from a special fine-grained layer produced on the surface during early stages of sliding. It is a very fine-grained material which may be derived from both parts of the materials system and may include components from the environment as well. Flake debris tends to originate from the fine-grained mixed layer and is formed by processes similar to mechanical alloying. Such processes include transfer, deformation, fracture, and blending [29]. "Compared with direct formation of loose wear debris, a fragment of material prefers transfer since the latter process gives rise to a further decrease in free energy of the system" [29]. When wear debris particles are generated from the mechanically-mixed layer, the layer is replenished by continuing transfer, smearing, and mixing. Under steady-state conditions these two processes would be balanced [20]. 
A few other terms which have been used to describe specific types of fatigue wear include extrusion wear which has been used to describe wear as a result of crack formation at the base of extruded wedges or lips. Cracks in certain materials systems have also been observed to occur in apparently random orientations. In reality there are so many different possible combinations of materials and conditions that many types of cracking and crack orientations may result due to the cyclic stressing in fatigue wear. Materials properties play a large role as do the types of stresses to which the materials are subjected. 
Factors which affect fatigue wear include the loading conditions, sliding speed, mechanical properties of the surfaces, debris which may be caught between the surfaces, and the mechanical properties of the film or highly deformed layer at the interface between the surfaces since the load must be transmitted through this interface or through this material. Fatigue wear is important in this study because none of the disks were perfectly round -- all had some amount of "total indicated runout" (TIR). Because of this TIR, additional cyclic loading stresses were present during testing. Lubrication can reduce fatigue wear by reducing the shear forces at the interface between opposing surfaces. 
2.3.6 Oxidative Wear 
The wear mechanisms already discussed (adhesive, abrasive, and fatigue) all result in material loss or at least the deformation of a surface. Oxidative wear, on the other hand, does not directly cause material loss or deformation. While oxidation is generally beneficial in sliding situations, this is not always the case. Oxidation is important because it can modify the wear surface in ways which can affect other wear mechanisms. 
Oxidation is the best known chemical reaction occurring at the surface of most metals, and it affects the wear process by changing the surface traction [30]. Oxidative wear involves the formation of a surface layer of oxide as a result of chemical reactions. It is the formation of this oxide film which can inhibit adhesion and thus reduce wear [31]. This layer can be removed with sliding, reformed, and removed again. This can continue indefinitely as long as conditions remain favorable. Nevertheless, an adhesive, abrasive, or fatigue mechanism is still required for wear to occur. 
An ideal situation for oxidative wear would be the dry sliding of metals under low loads. Under these conditions, the wear scar often appears smooth and has a shiny appearance. The overall wear rate is usually low and the wear debris particles generated are usually fine particles which are at least partly oxidized. The shiny wear scar frequently seen under these conditions is often an oxide layer. 
The oxidative wear mechanism is based on the assumption that the weakest point around the interface region of two mated materials is at the interface between the metal and its oxide. As a result, when sliding occurs, the oxide layer flakes off at the metal/metal oxide interface. Sliding contact at the asperities is what allows the oxide layer to flake off or be removed. At the asperity junctions, the local or flash temperature can be very large, especially when the sliding velocity exceeds about 1 m/s. These frictional heating effects can affect the rate of oxidation when sliding is in air and thus change the wear mechanism and wear rate [32]. Given the proper conditions (high enough temperature, enough time between cycles for the oxide to reform, etc.), the oxide can regrow on the same surface from which it was just removed. Oxidative wear is similar to the removal of a coating with very poor adhesion to its base material. The only difference is that in oxidative wear, the oxide has the ability (given the right conditions) to reform over and over again. 
Oxidative wear is favored under dry sliding conditions and low loads. When lubricants are used, the lubricant might contain elements which encourage even more oxide formation or it might serve as a barrier to chemical attack (by oxygen for example). In addition, a lubricant will generally reduce surface temperatures by lowering the friction and conducting heat away from the contact. Oxidative wear depends very much on the chemical reactivity of the surface, the chemical environment, and the surface temperature. 
Oxidative wear can prevent adhesive wear from occurring. If the load is sufficiently low, the oxide film which results from frictional heating can help prevent the formation of metallic bonds between the asperities of the sliding surfaces. In principle, this results in lower wear rates. As the load is increased, however, formation of metallic bonds between the asperities of mating surfaces occurs and much higher "adhesive" wear takes place. Though oxide formation is usually beneficial from a wear point of view, this is not always the case. Nevertheless, it is a very interesting fact that oxygen is probably the best lubricant available. Oxidation does occur, more or less, on the surface of metals and alloys during sliding in ambient air [33]. 
2.3.7 Physical Film Formation 
Physical film formation is similar to the oxidative wear mechanism in that a layer or film is developed. In oxidative wear the film is formed chemically, while physical film formation involves physical processes such as smearing. The film formed can be a transferred film, a third-body film, or contain some of each. Factors which influence the formation of this film include the roughness, geometry, load, sliding speed, temperature, and adhesion/materials properties of the rubbing surfaces. Similar to oxide film formation and removal, a physically formed film can change composition as wear progresses. It is often made from a combination of the two original sliding surfaces, oxides which have formed, and pieces of debris which may have accumulated and then gotten redistributed in this film. The actual film formed is unique to the materials involved, the testing conditions (or operating conditions in the case of actual machinery), and the overall tribosystem. 
Physically formed films can be very efficient in controlling wear and there are even instances where adding a lubricant will increase the wear rate of a given system which is known to rely on physical film formation to control wear. More is discussed on this physical film formation in terms of a "fine-grained mechanically mixed layer" in Section 2.3.9 -- Wear Mechanism Overview. Many automobile brake pad researchers believe that physical film formation (more of a glaze due to heating effects and the materials involved) between the brake pad and brake rotor/drum is the controlling factor in the performance of brake systems. 
2.3.8 Mild vs. Severe Wear 
Many tribologists like to refer to wear as being mild or severe. While the distinction has been made quantitatively in some wear equations, there are differences of opinion as to where one draws the line in these quantitative equations. I will only discuss these two regimes qualitatively. 
Mild wear has a much lower wear rate than severe wear and the wear scar generally has fine features. Severe wear has much higher wear rates and the wear scars generally have coarser features. Most materials can show both mild and severe wear depending on the tribosystem. The tribosystem consists of many factors including the geometry, loading conditions, materials used, sliding speed, and chemical environment. In addition, the wear mode can change from mild to severe or even from severe to mild. 
A transition from mild to severe wear could be caused by many things including an increase in the sliding speed, load, or a combination of these. These will both increase the temperature at the interface which can then affect things such as adhesion. An increased load might change the wear mode from oxidative wear to adhesive wear as the oxide film is ruptured, thus allowing metallic bonding between asperity contacts to occur. Many believe that transitions in wear rate are related to the formation or breaking through of surface films, particularly oxides [28]. 
Perhaps more important in the transition from mild to severe wear is the effect of hardening. Akagaki and Rigney found that for a pin-on-disk configuration, when the disk was harder than the pin, mild wear with smooth friction traces resulted. However, if the pin work hardened and became harder than the disk (as a general case involving two different materials or in the case of a self-mated system) this often led to a transition to severe wear with much rougher friction traces. It should be pointed out that a pin which was harder than the disk to begin with will also often lead to severe wear with rough friction traces. The time required for this transition to occur is very much dependent on all processes giving hardening [34]. 
Others such as Bowden and Tabor have found slightly different disk/pin hardness ratios (Akagaki's and Rigney's study found a critical ratio of 1) at which this transition occurs [35]. The point is that the relative hardness of the pin and disk can change during a test and thus affect the transition from mild to severe wear. Perhaps self-mated wear tests often lead to high wear rates and high friction coefficients because the pin material work hardens much more quickly than the disk material. This is because of more contact and deformation in the pin when compared to the disk. 
In the case where abrasive wear is dominant, a transition from mild to severe wear might occur due to an increase in the hardness of the abrasives. For example, the abrasives might work harden with continued sliding. Abrasive size, which can change with sliding, also affects wear. Ultrafine abrasives tend to polish while coarse abrasives lead to severe wear and create a rough wear scar with coarse grooves. Martensite formation might also cause a transition from mild to severe wear. In many systems or applications, one wants to try to avoid severe wear as it involves much higher maintenance and shorter service lives of equipment. 
2.3.9 Wear Mechanism Overview/Debris Generation 
The five wear mechanisms described were categorized for convenience. They should not be considered on an individual basis, but rather the ideas behind them should be used in conjunction with each other since the wear process is quite complex. It is the reasoning, chemistry, physics, mechanics, past data, prior tribotest results, and other evidence which led to their existence in the first place which is important. Nevertheless, five wear mechanisms which may be applicable to this research have been outlined. They are: 1. adhesive, 2. abrasive, 3. fatigue, 4. oxidative, and 5. physical film formation. This is far from a complete list of wear mechanisms proposed and some tribologists do not even agree with all of them, and instead suggest variations or combinations of them. Nevertheless, these 5 mechanisms cover a range of wear behavior appropriate for this research. To say all these wear mechanisms were definitely observed in this research would require a much more detailed study. This type of study would need many more samples studied in detail at intermediate sliding distances. Each tribological variable would need to be controlled with extreme care. 
Of the five wear mechanisms suggested, oxidative wear and physical film formation are best viewed as "wear modifiers" while the other three can be considered "basic" wear mechanisms. The "wear modifiers" can be thought to "affect or influence" the "basic" wear mechanisms. Considering the basic wear mechanisms of adhesion, abrasion, and fatigue wear, abrasive wear is generally the most severe. Thus it is favorable to try to avoid abrasive wear. One way this might be done is by using smoother surface finishes. 
It should be emphasized that while all the mechanisms were listed separately, in reality many or all (and there are many others which were not even mentioned) occur simultaneously. The wear process is quite complex and to view it as a simplified process can be misleading. Debris generation, for example, often involves local contacts, large plastic strains, changes in near-surface microstructure, localized shear, adhesion, mechanical mixing, transfer, deformation, fracture, blending, and the formation of a fine-grained mechanically mixed layer [24]. 
Models have been proposed which suggest that flake debris are generated when a critical layer thickness of this mechanically mixed layer is reached [36]. Flake debris usually are generated when the hardness of the fine-grained layer is less than the hardness of the "highly deformed" base material. In this case, the fine-grained layer is not able to press into the deformed layer and elevated plateaus are formed. It is from these elevated plateaus that the flakes are generated. This generally leads to a noisy friction trace and a rough wear scar [20]. 
When the hardness of the fine-grained layer produced on the surface is greater than the hardness of the "highly deformed" base material, more irregular (generally lamellar) debris can delaminate. The fine-grained layer should be hard enough to enable it to be pressed into the substrate for this irregular, non-flake debris to be generated [37]. This generally leads to a smoother friction trace and a smoother wear scar [20]. 
As this mechanically mixed layer is often the source of debris particles, the wear debris (except when microcutting is dominant) often have the same chemical composition, the same mix of phases, the same microstructure, and the same hardness as this mechanically mixed material on the sliding surface [29]. Any combination or even all of the wear mechanisms mentioned help create this mechanically mixed layer in the first place. 
LIST OF REFERENCES 
1.	B. Meyers, S. Lynn, and E. Jang, "Chromium Elimination," ASM Handbook [5] , Surface Engineering, 925-28, 1994. 
2.	R.A. Rapp, R. Bianco, and M.A. Harper, "Codepositing Elements by Halide-Activated Pack Cementation," J.O.M., [11], 20-25, (1991). 
3.	M.A. Harper, Codeposition of Chromium and Silicon Onto Iron- Base Alloys Via Pack Cementation, Ph.D. Thesis, The Ohio State University, 1992. 
4.	R.A. Rapp, and M.A. Harper, "Codeposition of Chromium and Silicon in Diffusion Coatings For Iron-Base Alloys Using Pack Cementation," Oxidation of Metals, [42, 3-4], 303-333, (1994). 
5.	C. Wagner, Corrosion Science, [5], 751-764, (1965). 
6.	M. Yu, Pack Cementation Cr23C6 Coating For Erosion, Corrosion And Oxidation Resistance Of H13 Die Steels, Ph.D. Thesis, The Ohio State University, 1994. 
7.	R.A. Rapp, "The Codeposition of Elements in Diffusion Coatings by the Pack Cementation Method," Materials at High Temperatures, [11], 181-184, (1993). 
8.	A.R. Miedema and F.J.A. den Broeder, Zeitschrift Metallk., [70], 14-20, (1979). 
9.	S. Timoshenko and J. Goodier, Theory of Elasticity, McGraw- Hill, New York, 1951.
10.	G. Hamilton and L.E. Goodman, "The Stress Field Created by a Circular Sliding Contact," J. App. Mech., 33(2), 371, (1966). 
11. W. Glaeser, Lecture notes, Wear Fundamentals Course for Engineering, Intl. Wear of Materials Conf., ASME, 1989. 
12.	E. Rabinowicz, Friction and Wear of Materials, John Wiley and Sons, New York, 50, 1965. 
13.	J. Ferrante, J. Smith and J. Rice, Microscopic Aspects of Adhesion and Lubrication, Elsevier Science Publishing Co., New York, Tribology Series, [7], 1982. 
14.	W.D. Callister, Jr., Materials Science and Engineering-An Introduction, John Wiley and Sons, Inc., New York, 15, 1985. 
15.	Y. Kimura "Some Problems in the Adhesion Theory of Friction," Fundamentals of Tribology, eds. N.P. Suh and N. Saka, The MIT Press, Cambridge, MA, 385-391, 1980. 
16.	D.A. Rigney, and P. Heilmann, "Reply to a Comment on 'An Energy-based Model of Friction and Its Application to Coated Systems'," Wear, [97] 303-309, (1984). 
17.	D.A. Rigney, M.G.S. Naylor, R. Divakar, and L.K. Ives, "Low Energy Dislocation Structures Caused by Sliding and by Particle Impact," Mat'ls. Sci. Engin., [81], 409-425. (1986). 
18.	D.A. Rigney, "The Role of Characterization in Understanding Debris Generation," Wear Particles, ed. D. Dowson et al., Elsevier Science Publishers, 405-412, 1992. 
19.	F.P. Bowden, A.J. Moore and D. Tabor, "The Ploughing and Adhesion of Sliding Metals," J. Appl. Phys., [14], 80-91, (1943). 
20.	D.A. Rigney, L.H. Chen, and M. Sawa, "Transfer and its Effects During Unlubricated Sliding," Metal Transfer and Galling in Metallic Systems, ed. H.D. Merchant and K.J. Bhansali, TMS- AIME, 87-102, 1987. 
21.	D.A. Rigney, and W.A. Glaeser, in Conference on Wear of Materials, St. Louis, Missouri, American Society of Mechanical Engineers, 41, 1977. 
22.	T.O. Mulhearn, and L.E. Samuels, "The Abrasion of Metals: A Model of the Process,"Wear, [5], 478-498, (1962). 
23.	D.A. Rigney, "Technical Note, Some Thoughts on Sliding Wear," Wear, 152, 187-192, (1992). 
24.	D.A. Rigney, "The Roles of Hardness in the Sliding Behavior of Materials," Wear, [175], 63-69, (1994). 
25.	L.E. Samuels, Metallographic Polishing by Mechanical Methods, Amer. Soc. for Metals, Metals Park, OH, 1988. 
26.	W.A. Glaeser, Proc. Int. Conf. Wear Mater., 155-162. New York: Am. Soc. Mech. Eng, 1987. 
27.	P.B. Blau, "Metallographic Evidence for the Nucleation of Subsurface Microcracks During Unlubricated Sliding of Metals," Wear, [117], 381-387, (1987). 
28.	D.A. Rigney, "Sliding Wear of Metals," Ann. Rev. Mater. Sci., [18], 141-63, (1988). 
29.	L.H. Chen, and D.A. Rigney, "Adhesion Theories of Transfer and Wear during Sliding of Metals," Wear, [136], 223-235, (1990). 
30.	N.P. Suh, "Wear Mechanisms: An Assessment of the State of Knowledge," Fundamentals of Tribology, eds. N.P. Suh and N. Saka, The MIT Press, Cambridge, MA, 443-453, 1980. 
31.	T.F.J. Quinn, "Review of Oxidational Wear, part I and II," Tribol. Int'l., [16], 257-271, 305-315, (1983). 
32.	D.A. Rigney, "Viewpoint Set on Materials Aspects of Wear- Introduction," Scripta Metallurgica, [24], 799-803, (1990). 
33.	A.R. Lansdown, in Interdisciplinary Approach to Liquid Lubricant Technology, NASA SP-318, 1973. 
34.	T Akagaki and D.A. Rigney, "Sliding Friction and Wear of Metals in Vacuum,"Wear, 149, 353-374, (1991), Also ref 42. 
35.	F.P. Bowden and D. Tabor, The Friction and Lubrication of Solids, [2], Oxford University Press, Oxford, 345-348, 1964. 
36.	J. Don and D.A. Rigney, "Prediction of Debris Flake Thickness," Wear, [105], 63-72, (1985). 
37.	D.A. Rigney, L.H. Chen and M.G.S. Naylor and A.R. Rosenfield, "Wear Processes in Sliding Systems," Wear, [100], 195-219, (1984). 
38.	Y. Naerheim, "A SEM/AES/XPS Tribometer for Rolling and Sliding Contacts," Wear, [162-164], 593-596, (1993). 
39.	G.N. Dubinin, Diffusion Chromizing of Alloys, Mashinostroenie Publishers, Moscow, 372, 1964. 
40.	Bearium Products, Inc., Huntington Park, Ca, Product Literature. 
41.	Phone conversation with Al Williams, Bearium Products, Inc, Huntington Park, Ca, 5-95. 
42.	T. Akagaki, and D.A. Rigney, "Sliding Friction and Wear of Metals in Vacuum," Proc. Intl. Conf on Wear of Matls., 1991, ASME, NY, 265-275, 1991, Also Ref 34.


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## Wow (May 17, 2010)

JT, If I read it, can I graduate with a masters degree in "Tribology"?


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## Bubbagon (Mar 8, 2010)

I was thinking the same thing. 
I did made it half way though. Maybe an Associates degree?


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## JamesT (Jul 22, 2005)

it depends

well wikipedia says that UHDPE has abrasion resistance 15X greater than low carbon steels.

hrummmph


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## JamesT (Jul 22, 2005)

Just don't use it as a 5th wheel and you'll be fine. If for some reason you do, go to the Meijer's clearance bin. Buy three tubes of anything (as long as it ends in oop) and apply liberally.


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## Wow (May 17, 2010)

That looks just like that kevlar / epoxy patch I saw on canoes at the livery, on the Mohican river, a few years back. Looks like dog crap spread with a butter knife. LOL.


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## Bubbagon (Mar 8, 2010)

All I see are glorious scratches.


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## Wow (May 17, 2010)

Bubbagon said:


> All I see are glorious scratches.


Where can I buy a pair of those rose colored glasses?


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## JamesT (Jul 22, 2005)

Not from Martha Stewart.


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## Bubbagon (Mar 8, 2010)

Wow said:


> Where can I buy a pair of those rose colored glasses?


The glasses are probably too dangerous for you. Maybe some shatterproof rose-colored goggles are more appropriate.


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## streamstalker (Jul 8, 2005)

This is what happens when you don't know enough about tribology:


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## Wow (May 17, 2010)

I think it's Bubba's current yak, nothing but cosmetic scratches. There's lots more years left in that thing.


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## JamesT (Jul 22, 2005)

llmmffaaoo!!!


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## Bubbagon (Mar 8, 2010)

LOL!! Actually mine look just a hair better.

My blue one:









And my red one:


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## crittergitter (Jun 9, 2005)

Bubba, those boats belong to a sexy beast! lol

You are having way to much fun with this.


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## streamstalker (Jul 8, 2005)

Yeah, I read about the demise of those Ultimates on Riversmallies....I have a feeling the poster left one key detail out of that story. I'm guessing he and his friend were floating on more than just the river that day.


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## Bubbagon (Mar 8, 2010)

I think the story goes that Ronnie didn't have them tied well enough on the back up someone's pick up and they were dragged behind the vehicle for several miles.
Quick! Someone go get some dogshit and a butter knife!!


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## Wow (May 17, 2010)

Are you sure those aren't Johnny Knoxville's?


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