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Tribology
Published in Milenko Braunovic, Valery V. Konchits, Nikolai K. Myshkin, Electrical Contacts, 2017
Milenko Braunovic, Valery V. Konchits, Nikolai K. Myshkin
This equation, often called the Archard wear equation, shows that the wear rate I (the volume worn per unit sliding distance) is directly proportional to the normal load P and inversely proportional to the hardness of the softer material H. The constant K, usually termed the wear coefficient, is dimensionless and always less than 1. K allows comparison of the severity of wear processes in different tribosystems. For engineering applications, it is often preferable to use the ratio K/H, termed the wear coefficient, dimensionally expressed as mm3/(N m). The measure of wear provided by the wear coefficient is particularly helpful when comparing wear rates in different classes of materials.
Wear Tests
Published in Raymond G. Bayer, Mechanical Wear Fundamentals and Testing, Revised and Expanded, 2004
great deal of flexibility in the load, sphere radius, speed, and materials used, as well as with the conditions surrounding the test (e.g., lubrication, temperature, and humidity). To a large degree, these parameters can be adjusted to simulate magnetic recording applications. However, the basic geometry of the contact situation and stress system are significantly different than in typical applications (e.g., those shown in Fig. 9.72). The method used to rank magnetic tapes in terms of their abrasivity is similar to that used for printer ribbons, namely, to determine a wear coefficient. This wear coefficient is the volume of wear divided by the product of the normal load, speed, and time of the test. The higher the value of this coefficient, the more abrasive the tape is.
Application Topics
Published in Q. Jane Wang, Dong Zhu, Interfacial Mechanics, 2019
where k is the so-called “wear coefficient”, and the three exponential constants, α, β, and γ, differ from one model to another. Table 14.5 summarizes the values of these exponents for some representative wear models among the many previously published theoretical and empirical wear laws. The wear coefficient differs due to material properties and operating conditions, to which each wear law is applicable.
Wear and frictional attributes of Al-alloy hybrid composite dispersed with hard-ceramic (ZrO2) and solid-lubricant (Gr) particles
Published in Journal of Dispersion Science and Technology, 2023
Ashish Kumar Singh, Sanjay Soni, Ravindra Singh Rana, Akshay Kumar, Girish Chandra, Raj Kumar Singh, Anil Kumar
Figure S2 depicts the relationship between applied pressure and wear coefficient for AA7068 alloy and various composites. Increasing the applied pressure from 0.5 MPa to 1.0 MPa resulted in a reduction in wear coefficient for all materials studied. However, as the pressure was further increased to 1.5 MPa, the wear coefficient for AA7068 alloy and composite (C1) increased slightly to 1.4 × 10−3 and 1.70 × 10−3, respectively, due to reaching the seizure stage. In contrast, composite (C3) exhibited a nearly constant wear coefficient within the pressure range of 1.0 MPa to 1.5 MPa, while composite (C2) and hybrid composites (HC1 and HC2) showed a slight increase in wear coefficient. It is worth noting that hybrid composites (HC1 and HC2) displayed low wear coefficient values of the order of 10−4 at an applied pressure of 1.5 MPa. The wear coefficient remained constant and varied within a narrow range at intermediate applied pressure values, reflecting a constant probability of wear debris formation. The wear coefficient is generally directly proportional to material hardness and inversely proportional to applied pressure. At higher pressures, the material is easily deformed, and strain hardening of the surface reduces the likelihood of debris formation.[44] For harder materials, however, the likelihood of fracturing is greater, leading to increased debris formation.
Wear Prediction of Earth-Moving Machinery Joint Bearing via Correlation between Wear Coefficient and Film Parameter: Experimental Study
Published in Tribology Transactions, 2018
Hong-Gyu Jeon, Dae-Hyun Cho, Jae-Hyeong Yoo, Young-Ze Lee
According to Archard's theory (Archard (12)), the steady-state wear volume in dry and lubricated sliding conditions can be quantified bywhere V is the wear volume, k represents the wear coefficient in the sliding condition, W denotes the normal load, S is the sliding distance, and H symbolizes the hardness. To obtain the wear coefficient or wear rate, the wear volume or weight loss is usually measured. However, in this study, the wear coefficient was calculated using modified Archard's theory due to the difference in contact type between the POD test and component test. The contact of the POD test and component test formed nonconformal and conformal contacts, respectively. Using the wear depth (hw) and Hertzian contact pressure (P), the wear characteristic in the sliding condition is quantified expressed by
Investigation of the wear resistance of in-situ Al-Ti composites fabricated by mechanical alloying and hot extrusion
Published in Canadian Metallurgical Quarterly, 2023
Arhard standard wear coefficient is computed using Arhard equation (1) where ΔV is the volume loss, H is the Brinell hardness, P is the vertical load and L is the sliding distance [22,26]. The wear coefficient is greatly affected by the wear mechanism and the wear rate. During a specific mechanism (until the wear mechanism has not changed), Arhard’s standard wear coefficient is constant. According to this equation, the wear rate (which is equal to ΔV/L) decreases with the increasing hardness at a specific mechanism [24]. Moreover, the wear resistance is directly related to the hardness of the material. Pournaderi and Akhlaghi [15] investigated Al6061/Al2O3 composites which were produced by an in-situ powder metallurgy (IPM). They did the wear test on samples with different percentages of Al2O3 by applying the force of 20 N and the sliding distances until 1000 m. They observed that the highest amount of hardness and the best wear behaviour was obtained in the sample with 15 wt-% of reinforcements. Eventually, they concluded that the wear resistance is directly proportional to the hardness, as shown in the Arhard relationship. Mostafa Akbari et al. [4] investigated the wear behaviour of Al-A365 metal matrix composites with particulate reinforcements such as B4C, SiC, TiC and ZrO2, which were fabricated by friction stir processing. They concluded that the wear behaviour of these composites is similar to the trend of hardness measurement. They also observed that the composites reinforced by TiC and ZrO2 particles which had the highest and lowest hardness values, respectively, had also the best and worst wear resistance.