Paper 17: Basic Mechanisms of Wear

1967 ◽  
Vol 182 (1) ◽  
pp. 281-292 ◽  
Author(s):  
W. Hirst
Keyword(s):  
Severe Wear ◽  
Wear Rates ◽  
Mild Wear ◽  
Dry Conditions

This review deals with the wear of conforming and non-conforming surfaces, both lubricated and dry. It covers the scuffing, pitting and mild wear of lubricated surfaces, the range of wear rates in dry conditions, the patterns of wear and the main causes of severe wear.

The dry wear of steels II. Interpretation and special features

1965 ◽  
Vol 257 (1077) ◽  
pp. 51-70 ◽  
Keyword(s):  
Oxide Film ◽  
Phase Change ◽  
Strain Hardening ◽  
Frictional Heating ◽  
Combined Effects ◽  
Phase Hardening ◽  
Special Effects ◽  
Severe Wear ◽  
Wear Rates ◽  
Mild Wear

The pattern of wear outlined in part I is interpreted in the light of further experiments which reveal that the change from severe wear to mild is governed by the hardness and state of oxidation of the surfaces. At light loads (< T 1) severe wear is inhibited by the combined effects of strain hardening and oxidation. At higher loads (> T 2) mild wear recurs primarily as a consequence of a change of phase induced by frictional heating. The hardness accompanying the phase change is great enough, initially, to suppress severe wear without the intervention of an oxide film. At loads immediately above T 2, however, the hardness tends to fall if rubbing is prolonged and oxidation is again essential to preserve the mild wear state. Sustained phase-hardening does not occur until a higher load, roughly coinciding with the T 3 transition, is attained and this finding has an important bearing on the influence of inert atmospheres. The onset of permanent hardening is not responsible for the divergent pin and ring wear rates at T 3, though the phenomena may be linked by the magnitude of the temperatures required to cause phase-hardening; the T 3 transition and the trend at higher loads have been identified as special effects associated with the thermal asymmetry of the rubbing system.

Predicting Bearing Performance of Filled Teflon TFE Resins

1967 ◽  
Vol 89 (1) ◽  
pp. 182-186 ◽  
Author(s):  
R. B. Lewis
Keyword(s):  
Surface Temperature ◽  
Bearing Surface ◽  
Temperature Dependent ◽  
Wear Factor ◽  
Severe Wear ◽  
Wear Rates ◽  
Surface Temperatures ◽  
Mild Wear ◽  
New Evidence

The wear rates of filled compositions of Teflon can be reliably predicted using an experimentally determined wear factor if the bearing pressure, velocity, temperature, and geometry are known. New evidence confirms the wear rates are directly proportional to pressure and velocity in both the mild wear regime and the severe wear regime, although the wear factors are much higher in the severe regime. The transition from mild to severe wear is pressure and surface temperature dependent and coincides with (but is not adequately described by) PV limit. An application factor is proposed to relate bearing surface temperatures to PV and geometry.

Transition of Mild Wear to Severe Wear in Oxidative Wear of H21 Steel

2008 ◽  
Vol 32 (2) ◽  
pp. 67-72 ◽  
Author(s):  
S. Q. Wang ◽  
M. X. Wei ◽  
F. Wang ◽  
X. H. Cui ◽  
C. Dong
Keyword(s):  
Oxidative Wear ◽  
Severe Wear ◽  
Mild Wear

TRIBOLOGICAL PROPERTIES OF THE CARBON AND NITROGEN-BASED HARD FILMS SLIDING AGAINST THE NICKEL-BASED SUPERALLOY

2020 ◽  
Vol 27 (08) ◽  
pp. 1950197
Author(s):  
X. L. LEI ◽  
B. X. YANG ◽  
Y. HE ◽  
F. H. SUN
Keyword(s):  
Tribological Properties ◽  
Cutting Tools ◽  
High Hardness ◽  
Wear Rates ◽  
Nickel Based Superalloy ◽  
Dlc Coating ◽  
Nano Crystalline ◽  
Debris Particles ◽  
Mild Wear ◽  
Super Alloy

This study is focused on the tribological properties of micro- and nano-crystalline diamond (MCD and NCD), non-hydrogenated and hydrogenated diamond-like carbon (DLC and DLC-H) and nitrogen-based (CrN, TiN and TiAlN) coatings sliding against the super alloy Inconel 718, in terms of the maximal and average coefficients of frictions (COFs), the worn morphologies and the specific wear rates, by the rotating ball-on-plate configuration under dry condition. The results show that the nitrogen-based films show comparable COFs and wear rates with the WC–Co substrates. The DLC and DLC-H show lower COFs compared with the nitrogen-based films. Furthermore, their wear resistance is limited due to their low thickness compared with MCD and NCD, which have the same elemental composition. The DLC-H coating exhibits much lower wear rate compared with the DLC coating, which may be derived from the passivation of dangling bonds by the linking of H to C atoms. The MCD and NCD films show the lowest average COFs and mild wear after tribotests, due to their high hardness and low adhesive strength between pure diamond and the super alloy. Among all the tested films, the NCD film-based tribopair presents the lowest maximal and average COFs, tiny wear debris particles, mild wear of ball and plate without scratching grooves, indicating that the NCD film may be suitable to be deposited on cutting tools for super alloy machining.

Tribological behaviour of hypereutectic Al-Si automotive cylinder liner material under dry sliding wear condition in severe wear regime

2020 ◽  
pp. 135065012096461
Author(s):  
Ajith Kurian Baby ◽  
M Priyaranjan ◽  
K Deepak Lawrence ◽  
PK Rajendrakumar
Keyword(s):  
Surface Morphology ◽  
Wear Behaviour ◽  
Dry Sliding Wear ◽  
Dry Sliding ◽  
Liner Material ◽  
Severe Wear ◽  
Mild Wear ◽  
The Matrix ◽  
Pin On Disk ◽  
Silicon Particles

Hypereutectic Al-Si alloys are used as material for the engine block and cylinder liners in automobiles. Wear behaviour of hypereutectic Al-Si alloy system changes significantly with applied normal load in both mild wear and severe wear regime. Significant improvement in wear resistance can be obtained by exposing silicon particles through the chemical etching process. For Al-25% Si alloys, most studies are reported in mild and ultra-mild wear regime. In the present work, the wear of exposed silicon particles with varying load and speed in severe wear regime was investigated under the unidirectional sliding condition and bi-directional sliding condition using a pin-on-disk tribometer (POD) and a linear reciprocating tribometer (LRT), respectively. Rapidly solidified and T6 heat-treated Al-25Si alloy was polished and etched using 5% NaOH solution to expose the silicon particles. Experiments were carried out with normal loads varying from 40 N to 120 N in dry sliding conditions. Sliding speeds of 0.8 m/s and 1.5 m/s were applied for each load in case of a pin on disk tribometer whereas, in an LRT, the sliding velocities were 0.2 m/s and 0.45 m/s respectively for each set of the load. The surface topography was measured by means of a 3-D optical profilometer, and surface morphology was analyzed using SEM images. It was observed that at higher loads, larger Si particles were fractured and pushed into the matrix. Fractured silicon particles, along with smaller particles, were embedded into the matrix, thereby increasing the silicon concentration in the wear region. The comparison of the experimental results of unidirectional and bi-directional sliding that reveal the change in surface morphology of silicon particles, the friction characteristics at the interface, variation of surface 3-D roughness parameters, the wear rate and wear mechanisms of Al-25% Si alloys are analyzed and reported in the study.

Influence of Mechanical and Chemical Factors on Transition Between Severe and Mild Wear in Saline Solution

1997 ◽  
Vol 119 (4) ◽  
pp. 619-625 ◽  
Author(s):  
H. Goto
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Content ◽  
Cathodic Protection ◽  
Saline Solution ◽  
Concentration Level ◽  
Applied Potential ◽  
Severe Wear ◽  
Saturated Condition ◽  
Mild Wear ◽  
Chemical Factors

Pin-on-disk wear tests of carbon steels in saline solution were carried out at high loads to study the effects of mechanical and chemical factors on the transition between severe and mild wear. The factors were load, presliding time, concentration of saline solution, dissolved oxygen content, and applied potential for cathodic protection. Severe wear and seizure appear at low concentration levels of saline solution and the transition takes place at a certain concentration level of saline solution. The concentration level for the transition is higher under argon-saturated condition than under air-saturated condition. Mild wear is predominant over the whole range of dissolved oxygen content from 0.5 to 18 ppm in 0.5 wt percent saline solution and the wear rate decreases with decreasing dissolved oxygen content. The mild wear occurs in the range from 2 to 18 ppm in 0.01 wt percent saline solution, whereas the wear mode moves to severe wear below 2 ppm. Mild wear predominates under incomplete cathodic protection between −0.50 and −0.80 V (versus Ag/AgCl in 0.5 wt percent saline solution. The applied potential for the transition from initial to steady wear is more negative under higher dissolved oxygen content condition. Complete severe wear occurs below −0.90 V (versus Ag/AgCl) with a risk of seizure.

Elevated Temperature Wear of Submicron Al2O3 Reinforced 6061 Aluminum Composite

2009 ◽  
Vol 83-86 ◽  
pp. 1288-1296
Author(s):  
A.M. Al-Qutub ◽  
I. Allam ◽  
A. Al Hamed ◽  
A. Elaiche
Keyword(s):  
Elevated Temperatures ◽  
Wear Behavior ◽  
Material Transfer ◽  
Alloy Matrix ◽  
Aluminum Composite ◽  
Severe Wear ◽  
Wear Rates ◽  
The Matrix ◽  
Steel Disc ◽  
Temperature Scanning

The effects of load and temperature on wear behavior of 6061 Aluminum alloy matrix composite reinforced with 20% Al2O3 (submicron) particulates against AISI 4041 steel disc were studied at elevated temperatures ranging from 25oC to 300oC. Mild and severe wear regions separated by a transition region were observed at all temperatures with a difference of two orders of magnitude between mild and severe wear. The critical loads observed at 100oC, 200oC and 300oC were 40 N (2 MPa), 30 N (1.53 MPa) and 15 N (0.76 MPa) respectively indicating that wear resistance of the composite decreases with increase in temperature. Scanning electron microscopy revealed that wear was accompanied by extensive thermal softening of the matrix, in addition to particulate fracture due to high shear strain generated from the contacts and material transfer to the counterface. The wear rates were reduced in the mild wear regime due to oxidation of the iron counterface and deposition of oxides on the contact surfaces evident by EDS analysis.

Tribological Characteristics of Deformed Magnesium Alloy AZ61 Under Dry Conditions

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Abdel-Wahab El-Morsy ◽  
A. Abouel-Kasem
Keyword(s):  
Magnesium Alloy ◽  
Wear Rate ◽  
Deformation Process ◽  
Wear Behavior ◽  
Sliding Velocity ◽  
Wear Rates ◽  
Power Spectral ◽  
Dry Conditions ◽  
The Relationship ◽  
Applied Stresses

The wear behavior of deformed magnesium alloy AZ61 under dry conditions was evaluated. Two types of AZ61 alloy were used, extruded and rolled samples, to investigate the effect of deformation process on the wear behavior. The experiments were performed using a pin-on-ring type wear apparatus against a stainless-steel counterface under applied stresses in the range of 3–7 MPa, and within a sliding velocity range of 0.2–1.8 m/s. The topographical images of the eroded surfaces at different sliding velocity for extruded and rolled samples were quantified using fractal analysis. The results revealed that for all applied stress, the wear rates increased with increasing the sliding velocity of both samples. The wear rate of the rolled samples is greater than that of the extruded samples at the stress range from 3 to 5 MPa. However, when the stress is increased to 7 MPa the wear rate of the rolled samples is lower than that of the extruded samples. The variation of fractal value of slope of linearized power spectral density (PSD) with the sliding velocity is largely similar to the relationship between the wear rate and the sliding velocity.

Dry Sliding Wear Behavior of EB Surface-Alloyed and Dispersed AZ91 Magnesium Alloy under Mild Wear Conditions

2015 ◽  
Vol 828-829 ◽  
pp. 272-278
Author(s):  
Katja Fritzsch ◽  
Anja Buchwalder ◽  
Rolf Zenker
Keyword(s):  
Electron Beam ◽  
Wear Behavior ◽  
Base Material ◽  
Dry Sliding Wear ◽  
Az91 Magnesium Alloy ◽  
Wear Rates ◽  
Beneficial Effects ◽  
Mild Wear ◽  
Az91 Magnesium ◽  
Sliding Distance

This paper reports on investigations of the beneficial effects of electron beam alloying (EBA) and electron beam dispersion alloying (EBDA) on the wear behavior of AZ91D Mg alloy under mild wear conditions with applied normal loads of 1…10 N. The layers generated had a thickness of 1.5 mm with Al contents of 30 wt.%. For dispersion alloyed layers, TiC was added with particle sizes of 20…100 µm. At a sliding distance of 20 m, the wear rates of alloyed layers (150 HB) and dispersion alloyed layers (180 HB) were almost the same and could be reduced by half compared to the untreated AZ91D (60 HB). Due to their large size and the large spaces between them, TiC particles were pressed into the layer matrix, or were torn out and acted as additional abrasives. Therefore, at a sliding distance of 50 m, the wear rate of dispersion alloyed layers increased to the level of the base material.

Influence of Car Tonnage and Wheel Adhesion on Rail and Wheel Wear: A Laboratory Study

1986 ◽  
Vol 108 (1) ◽  
pp. 48-58 ◽  
Author(s):  
S. Kumar ◽  
P. K. Krishnamoorthy ◽  
D. L. Prasanna Rao
Keyword(s):  
Wear Rate ◽  
Wheel Wear ◽  
Wheel Load ◽  
Adhesion Coefficient ◽  
Wear Rates ◽  
Bilinear Relation ◽  
Mild Wear ◽  
Rate Versus ◽  
Freight Car ◽  
Plastic Shakedown

This study presents the results and analysis of a laboratory investigation, of rail and wheel wear under clean and dry tangent track conditions, utilizing the IIT-GMEMD quarter scale simulation facility. Important factors influencing rail degradation are discussed followed by five different load/lubrication classifications of contacts. Influence of two important parameters, viz. wheel load (N) and adhesion coefficient of the tractive wheels (μ), on rail and wheel wear has been studied under conditions of Hertzian simulation. Seven separate experiments were conducted to measure wear of rail and nontractive freight car wheels. These were followed by six additional wear tests, simulating a typical U.S. locomotive, to investigate the effect of adhesion coefficients. The wear rates for tonnages* exceeding 65–70 t car increase at a much higher rate than those for tonnages below 65 t. Nonlinear relationship showing wear rate proportional to N5.4 and a bilinear relation have been developed. Considerations of contact plasticity show that the stress corresponding to 68-t freight load is a threshold stress which when exceeded leads to continual plasticity of new rails thus preventing shakedown. The influence of adhesion coefficient is also quite nonlinear, the wear rates being much higher for μ &gt; 0.3. Photomicrographs of the surfaces of the wheel and rail at the end of the tests showed mild wear for μ ≤ 0.25 and severe wear for μ ≥ 0.35 indicating a transition of wear mechanism from mild to severe slightly above μ = 0.25. Wear rate is found to be approximately proportional to the square of the adhesion coefficient. A bilinear relation of wear rate versus μ, which is more accurate, is also given. It was observed that the effect of adhesion is more severe than the effect of tonnage alone. However, the tonnage effect is of serious consequence regarding plastic shakedown of the rails. A formulation of wear rate as a combined function of tonnage and adhesion coefficient is given. The urgent need for a solution of this problem is pointed out.

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