Wear Mechanism Map Research Articles

Ceramic wear maps

Ceramic wear maps have been developed to elucidate the complex interactions of the operating parameters, environments, and wear mechanisms. This paper summarizes these interactions for four ceramics, alumina, yttria-doped zirconia, silicon carbide and silicon nitride. Wear maps of these ceramics are systematically constructed using measured data under dry sliding, water, and paraffin lubricated conditions. For each material, different wear level regions and wear transition zones are identified as a function of operating conditions and lubrication conditions. Wear mechanism studies performed within each wear region give rise to the wear mechanism maps. These maps facilitate material comparison and selection. The knowledge of wear, wear transitions, and wear mechanisms for a material pair enables realistic wear model development. One outcome of this approach is the recognition that a single wear model for a material pair cannot cover all operating conditions and environments. As wear maps are constructed today, they are material pair specific. Within a material pair, there are microstructural dependence and surface properties influence. These parameters can change substantially for a given chemical composition of the material. How to incorporate these factors into the wear map research remains an issue. The search for a universal parameter such as the “asperity temperature” in Ashby's wear map continues in spite of mounting evidence that this may not be practical or feasible. But the hope remains that some parameters can be identified to normalize a large number of materials, operating conditions, and environments for tribological applications. Systematic wear maps are the first steps in this direction.

Reciprocal sliding wear of SiC particle-reinforced AlCu aluminium matrix composites against stainless steel, high speed tool steel and ceramics II. Wear mechanisms

The friction and wear of AlCuSiC aluminium matrix composite pins dry sliding against 4Cr 13, W 18Cr 4V and Si 3N 4(SN) ceramic blocks were investigated in a reciprocal friction test machine under applied loads of 20–175 N and reciprocal speeds of 0.075–1.2 ms −1. The wom surface morphology was analysed to clarify the wear mechanisms. Wear mechanism maps were constructed to elucidate the effects of test condition such as applied load, reciprocal speed and counterface materials on the wear mode and wear mechanism transition. Wear models were proposed to explain the experimental phenomena based on the characterization studies.

On wear characteristics of leaded aluminium-silicon alloys

Wear characteristics of Al-Si-Pb alloys with silicon content from 2 to 20 wt% and lead from 2 to 10 wt% have been studied using a pin-on-disc type wear testing machine at room temperature. The effects of applied load, sliding velocity and alloy composition on wear rate of Al-Si-Pb alloys have been investigated. It has been found that wear rate is strongly dependent on alloy composition, applied load and sliding speed. Wear rate decreases and load bearing capacity of the alloy increases with increase in lead content. Wear rate of Al-Si-Pb alloys initially decreases and then increases with increase in sliding speed. Wear mechanism map predicting nature of the wear processes can be prepared for aluminium alloys.

On the influence of strain rate sensitivity on wear in the Archard regime

Relating wear characteristics of a metallic material to its mechanical properties (yield strength, strain hardening coefficient) and its microstructural features (size and volume fraction of inclusions) is a long-standing problem. The diversity of mechanisms which are involved during wear processes makes it practically impossible to have a general theory which would encompass all thinkable situations corresponding to various loads and various regimes of sliding. Different regimes and the conditions for their occurrence have been systematized in wear mechanism maps. In this communication the authors are going to restrict their consideration to plasticity dominated wear which is expected to occur in the low velocity range where surface heating is negligible. In this regime, the prevalent wear mechanism is the removal of slivers of metal by plastic failure due to shearing of contact asperities. The classic works by Rabinowicz have demonstrated clearly that solid friction is a rate dependent problem and that the velocity dependence of dynamic solid friction is nothing else than a consequence of the increase of static solid friction with time during which normal load was applied prior to the commencement of sliding. Creep under normal compression stress leads to flattening of the junctions causing their strength to increasemore » with time. Like solid friction, wear appears to be a rate dependent phenomenon, and the strain rate sensitivity of the flow stress can be expected to be relevant for wear resistance. The strain rate sensitivity is known to play an important role in other damage related properties, such as ductility and fracture toughness. The authors felt that it would be of interest to evaluate the effect of strain rate sensitivity on the wear rate as part of an attempt to relate the wear properties to a bulk constitutive equation, and as a guideline for assessing the influence of alloying elements known to affect the strain rate sensitivity.« less

Wear mechanism map of nitrided steel

Wear maps for untreated and gas nitrided BS970,905M39 (EN41B) steels have been constructed, which show the dominant wear mechanism regimes. The wear studies were carried out using a pin-on-disc machine under unlubricated conditions over a wide range of sliding speed and applied load, and the wear mechanisms were determined by examination of the worn specimens and wear debris. A sharp wear rate transition between mild (oxidative) and severe (metallic) regimes was identified for both untreated and gas nitrided steels. Gas nitriding expanded the mild wear region toward higher loads and sliding speeds.

Galling in aluminum alloys and Duralcan aluminum matrix composites

Galling behaviour of Duralcan TM aluminum matrix composites (metal matrix composites (MMCs): 20 vol.% SiC in an Al-Si alloy matrix) is compared with that of unreinforced 6061 aluminum alloy and cast iron. Counterface materials were 52100 bearing steel and cart iron with test conditions consisting of cylinders of the ferrous materials sliding on plates of the aluminum based materials, in reciprocating motion without lubrication. The onset of galling was studied in a stepped load test. Neither the 52100 steel sliding on cast iron, nor the cast iron sliding on the MMC exhibited galling through the range of loads tested. Instead they exhibited uniform, rectangular wear tracks consistent with truncation of surface asperities and increasing conformity of the surfaces as wear progressed. The unreinforced 6061 alloy, exhibited galling at low loads with protrusions forming on the hard steel slider that caused abrasion of the aluminum alloy. Thus conformity of contact decreased as wear progressed. Galling is discussed in relation to contact geometry and wear mechanism maps.

Wear mechanism maps of 440C martensitic stainless steel

AISI 440C martensitic stainless steel is the material of choice for the high pressure oxygen turbopump (HPOTP) of the space shuttle main engine (SSME). Tests have been done over a range of sliding speeds from 0.5 to 2.0 m s −1, initial hertzian stresses from 0.915 to 3.66 GPa, and bulk temperatures from −184 °C (liquid oxygen temperature) to 760 °C, which cover the variations thought to exist in the HPOTP. Data are presented in the form of contour wear maps to allow a more direct view of the interdependencies of the major tribological variables than can be obtained with wear data presented vs. a single variable. Wear maps are used as a tool to aid in the determination of regions dominated by a given wear mode. Parametric combinations that result in transitions between wear modes are more easily detected with the use of wear maps. Wear maps can simplify design by identifying combinations of speed, load, and bulk temperature that need to be avoided, because of undesirable wear modes.

Wear mechanisms in brittle solids

The wear mechanisms of brittle ceramic and polymer surfaces have been studied. The tests span a wide range of sliding velocities—from 0.001 to 20 m/s. At the slower speeds the two surfaces remain completely cold, even on the scale of contacting asperities; at the highest speeds bulk heating is considerable and contact temperatures exceed the melting point. The appearance of the wear tracks correlates with the computed temperatures at the sliding contact. Models for wear damage are reviewed and related to these temperatures. The wear observations are summarised as a tentative wear-mechanism map.

Some considerations towards the design of a wear resistant aluminium alloy

The properties of light weight and wear resistance seldom go together. The resistance of aluminium alloys to sliding wear could be increased by identifying the basic mechanisms of wear and the factors influencing them. As a first step towards a perspective understanding, a wear mechanism map of aluminium alloys was produced. This paper attempts to relate material properties such as hardness and toughness to the wear rate of aluminium alloys under particular load and speed conditions. Hardness seems to be important in the wear regime of equiaxed particle formation while toughness controls the delamination type of wear. The influence of microstructure on hardness and toughness and thus on the wear resistance of aluminium alloys is discussed. A processing method involving rapid solidification and mechanical alloying to achieve a very fine microstructure in aluminium alloys is outlined.

The Friction and Wear of Lubricated Si3N4/SiC(w) Composites

The friction and wear of a 20 via silicon carbide whisker-silicon nitride matrix composite was measured at room temperature in both lubricated and unlubricated sliding. A pin-on-disk test configuration was used in which the pin member was a 9.53 mm diameter sphere. Silicon carbide and silicon nitride spheres were tested against the composite in both unidirectional and reciprocating sliding. The range of experimental parameters included normal forces from 1 to 45 N, velocities of 0.1 and 0.3 m/s and test durations of five minutes to three hours. The lubricant used in the room temperature tests was a commercial synthetic, fully formulated engine oil (5W30). In unlubricated sliding, silicon nitride produced more severe wear of the composite than did silicon carbide. In lubricated sliding, very little wear occurs in either sliding pair at even the longest test exposure. The data are presented in “wear space” co-ordinates and this form of presentation is compared to other wear mechanism map concepts presently ...

A Transition Diagram for Plain Journal Bearings

On the basis of experimental data in terms of Stribeck curves and a few simple principles from lubrication and heat transfer theories, transition diagrams for plain journal bearings, operating under conditions of moving contact, have been constructed. These diagrams relate the condition of lubrication, i.e. (elasto) hydrodynamic, mixed, boundary or 'unlubricated' to radial force F and sliding speed v. They may be used to predict load carrying capacity at high speeds and they may also serve as 'wear mechanism maps.' Presented at the 35th STLE/ASME Tribology Conference in Fort Lauderdale, Florida October 16–19, 1989

Wear mechanism map for aluminium alloys

Etablissement des cartes de mecanisme d'usure a partir de donnees se trouvant dans trois categories: les donnees concernant l'usure, par glissement de Al et des alliages Al-Si sur de l'acier, les donnees obtenues par des essais a haute vitesse, utilisant des projectiles de poudre explosive, les donnees identifiant les mecanismes d'usure a partir de l'etude des surfaces et des debris d'usure