High Wear Research Articles

Investigating the Mechanical and Tribological Properties of Bio-Waste Derived Bioactive Borosilicate Glass Incorporating Strontium Oxide

Abstract The primary goal of the current research paper is to investigate the mechanical and tribological behavior of biologically active glass consisting of 31B2O3-(20-x) SiO2-24.5Na2O-24.5CaO and xSrO (in mol%). The specimens were fabricated partly using bio-waste material, in which Silica and Calcium Oxide were derived from rice husks and egg shells, respectively. The produced specimens underwent immersion in simulated bodily fluid for a week to observe their bioactive response. The bioactive behavior of the samples were examined using X-ray diffraction and FTIR spectroscopy. The compression test and hardness of the specimens were measured using universal testing machine and Vickers micro-hardness tester. Abrasion test of the specimens were performed on pin-on-disc tribometer and the worn-out surfaces were later analyzed using FESEM. The findings from FTIR and XRD analyses validated the existence of a hydroxyapatite layer on the specimen surfaces. Further, XRD data showed an increase in peak intensity after SrO was incorporated, suggesting that it played a supporting role in boosting bioactivity. The mechanical investigations indicated that the addition of SrO adversely affects both hardness and compression strength. The abrasion wear test demonstrated that BSG-5 had the highest wear rate, while BSG-0 exhibited the lowest wear rate among all specimens at a 30 mm track radius. Despite the trade-off between enhanced bioactivity and diminished mechanical strength and wear resistance, incorporating Strontium Oxide makes the glass suitable for applications prioritizing bioactivity, such as bone filling and dental contexts.

Granular polyacrylonitrile with internal 3D channels for gold recovery from thiosulfate solution

Gold recovery technology is an urgent challenge in the industrialisation of thiosulfate-based gold extraction. Current materials used for gold recovery suffer from a lack of wear resistance and small particle size, which makes it difficult to separate the material from thiosulfate solutions. In this study, a cysteamine-functionalised granular polyacrylonitrile (cys-PANG) material containing three-dimensional channels was designed and synthesised. The results indicate that cys-PANG, prepared using a solvent exchange method, has remarkable adsorption capacity for gold, smooth outer surface, well-developed internal pore structure, high wear resistance, and controllable size, making it suitable for gold recovery from thiosulfate pulp. The adsorption of gold in a thiosulfate solution by cys-PANG followed the Freundlich isotherm and pseudo-second-order kinetic adsorption models with minimal pH dependence. Cys-PANG also demonstrated the effective adsorption of gold in a Cu(II)–ethanediamine (en)–S2O32− solution, even in the presence of copper and en interference. Both experimental results and theoretical calculations revealed that the interaction between cys-PANG and gold in the thiosulfate solution is predominantly characterised by charge attraction and ligand exchange mechanisms. Adsorption tests of cys-PANG in actual thiosulfate pulp demonstrated exceptional gold recovery properties and minimal wear even after 14 days of continuous stirring. This study presents a promising alternative methodology for the recovery of gold from thiosulfate pulp.

3 Body abrasion test of HVOF sprayed WC-10Co-4Cr and WC-10Co-4Cr + 2 % graphene coating on IS-2062 steel

This study investigates the microstructural characteristics, mechanical properties, and slurry abrasion resistance of WC-10Co-4Cr and WC-10Co-4Cr + GNPs coatings deposited using the High-Velocity Oxy-Fuel (HVOF) process. Cross-sectional micrographs, EDS line scans, and spectra reveal uniform distribution and proper adhesion of tungsten carbide particles, cobalt, chromium, and graphene nanoplatelets (GNPs) throughout the WC-10Co-4Cr + GNPs coating. Microstructural analysis indicates denser structure and reduced porosity in the WC-10Co-4Cr + GNPs coating, leading to enhanced abrasion resistance. Mechanical testing demonstrates higher microhardness and bond strength in the WC-10Co-4Cr + GNPs coating, attributed to the incorporation of GNPs and Laser Surface Texturing (LST). Slurry abrasion tests show substantial reductions in mass loss for both coatings compared to the pristine substrate, with the WC-10Co-4Cr + GNPs coating exhibiting superior performance due to its densification and lubrication effect of GNPs. Overall, the WC-10Co-4Cr + GNPs coating presents a promising solution for applications requiring high wear resistance and durability in harsh environments.

ТРИБОТЕХНИЧЕСКИЕ ИССЛЕДОВАНИЯ ВТОРИЧНЫХ БРОНЗОВЫХ ПОКРЫТИЙ

One of the features of agricultural machines is the use of a sufficiently large number of parts made of non-ferrous metals and alloys in their designs, since they have high antifriction properties, corrosion resistance, withstand significant specific loads and high speed conditions. Most often these are bronze plain bearings of the bushing type. Tribotechnical studies of coated samples based on secondary composite materials on a friction machine is an important direction in the development of technologies for the restoration and hardening of bronze parts and assemblies. Secondary composite materials are obtained from production waste by the electroerosion dispersion, which allows to reduce production costs and reduce the environmental burden. Such powders can be used to create repair coatings with high wear resistance. (Research purpose) The research purpose is performing a comparative analysis of the tribotechnical properties of coatings obtained usng secondary composite materials and electric spark processing. (Materials and methods) Samples with bronze coatings were produced for research. Conducted tests on the friction machine II5018. (Results and discussion) It was determined that coated samples based on secondary composite materials have higher wear resistance and less friction compared to uncoated samples. It was found that with increasing load and sliding speed, the difference in wear resistance and friction between coated and uncoated samples increases. The coating based on secondary composite materials is especially effective in conditions of high loads and sliding speeds. (Conclusions) Comparative tribotechnical studies of coated samples based on secondary composite materials have shown that such coatings can be an effective way to increase wear resistance and reduce friction in various machine components.

Machining characteristics and optimization of 10CrNi3Mo alloy steel by WEDM

ABSTRACT 10CrNi3Mo alloy steel has the characteristics of high hardness and wear resistance, and is widely used in aircraft and spacecraft, shipbuilding and so on. However, its conventional processing method has high tool loss. Wire Electrical Discharge Machining (WEDM) technology is based on electrode pulse discharge to corrode materials. There is no direct contact between the tool and the workpiece, so it is suitable for processing materials with complex shapes, such as high hardness and high brittleness. The focus of this study is to investigate the effects of different electrical parameters such as pulse width, pulse gap, current, and wire feeding speed on the recast layer thickness (RCL) and surface roughness (SR) of 10CrNi3Mo alloy steel processed by wire discharge machining using orthogonal experiments. The gray correlation method was used to optimize the above two process indicators, and seeking optimal processing parameters. The optimized recast layer thickness was 8.65 μ m. The surface roughness is 1.932 μ m. Achieve expected goals.

Experimental Studies of the Machinability of SiCp/Al with Different Volume Fractions under Ultrasonic-Assisted Grinding.

High-volume fraction silicon carbide particle-reinforced aluminum (SiCp/Al) has a promising application for its high specific strength, wear resistance, and thermal conductivity. However, SiCp/Al components with a high-volume fraction are prone to poor surface quality and defects such as fractures, cracks, and micro-pits. It has been reported that ultrasonic-assisted grinding machining (UAG) helps to improve the quality of SiCp/Al machined surfaces. However, the differences between SiCp/Al with different volume fractions obtained by UAG machining are not clear. Therefore, a comparative study of surface roughness, morphology, and cutting force was carried out by UAG machining on SiCp/Al samples with volume fractions of 45% and 60%. Compared to the 45% volume fraction SiCp/Al, the 60% volume fraction SiCp/Al has a higher cutting force and roughness under the same machining parameters. In addition, experiments have shown that cutting forces and surface roughness can be reduced by increasing the tool speed or decreasing the feed rate. UAG machining with an ultrasonic amplitude within 4 μm can also reduce cutting forces and surface roughness. However, more than 6 μm ultrasonic amplitude may lead to an increase in roughness. This study contributes to reasonable parameter settings in ultrasonically-assisted grinding of SiCp/Al with different volume fractions.

A simple and feasible method for preparing chromium carbide coating on graphite through binary NaCl-KCl molten salt

Due to excellent high temperatures resistance and wear resistance, graphite showed great potential apply in refractory materials. However, the porosity defects caused by the layered stacked structure of graphite would lead to easy permeability, which would result in reducing material’s lifetime. Surface coating technology was considered to be an ideal method to solve the problems through a stable coating on the surface of graphite. But existing methods have some disadvantages, such as high-cost and complex processes. In this work, a simple, low-cost and green molten salt method was designed. This method successfully prepared a Cr7C3 coating on the graphite surface. The effect of reaction time and temperatures on the chromium carbide coating was investigated by SEM and EDS. The results showed that the thickness of the coating layer increased gradually with the increase in reaction time or reaction temperature, and finally stabilized at about 8 μm. In addition, the reasons behind the formation of Cr7C3 coatings were discussed in terms of both the molten salt reaction and Gibbs free energy, as well as the effect of the coating structure on adhesion. Based on this method, it could not only effectively address the structure defects of graphite, but also showed simple preparation processes and low cost, which would promote the development of graphite materials in high-temperature resistant materials.

Enhancing Tribological Performance of Micro-Arc Oxidation Coatings on 6061 Aluminum Alloy with h-BN Incorporation

Micro-arc oxidation (MAO) coatings of aluminum alloy have great potential applications due to their high hardness and wear resistance. However, the micro-pores and defects formed in the discharge channels during the MAO process limit its application in the corrosion field. This study delves into the impact of h-BN nanoparticles into MAO coatings on their structure, corrosion resistance, phase composition, and tribological properties. The results show that the incorporation of h-BN particles reduces the porosity and surface roughness of the coating while enhancing its hardness and wear resistance. The best corrosion resistance is obtained at a concentration of 2 g/L h-BN. An analysis of worn surface morphology, corrosion resistance, and friction coefficient change was conducted to evaluate the performance of this coating. This method provides a new approach to enhance the surface hardness and wear resistance of aluminum alloys, which is significant for expanding the application of aluminum alloys in corrosion environments.

Quantification of the sp3 content in Diamond-Like carbon Films: Effects of Ne plasma addition in Deep Oscillation Magnetron sputtering

Diamond-like carbon (DLC) films are a class of amorphous carbon materials with unique properties, including high hardness and wear resistance, making them attractive for aerospace and automotive applications. Recently, High Power Impulse Magnetron Sputtering (HiPIMS) has emerged as a new route for magnetron-sputtered hard DLC films. The authors have previously demonstrated that adding Ne to the plasma significantly improves the properties of DLC films deposited by Deep Oscillation Magnetron Sputtering (DOMS), a HiPIMS variant. In this study, the sp3 content evolution with DLC film thickness was measured by Electron Energy Loss Spectroscopy (EELS) and Near Edge X-ray Absorption Spectroscopy (NEXAFS). The sp3 content in the top section of the film deposited in Ar + Ne plasma is close to 40 % and remains constant across the film thickness. Conversely, in films deposited in pure Ar plasma, the sp3 content decreases from approximately 30 % to 18 % towards the surface. Ne addition increases the sp3 content by enhancing the carbon ion flux and counteracting the atomic shadowing effect. These findings provide novel insights into the role of Ne in reducing the atomic shadowing effect and improving the overall quality of DLC films, paving the way for their optimized industrial use.

Implications of FCC and HCP cobalt phases on wear performance of weld deposited cobalt-based coating

SS316L possesses comparatively low wear and abrasion resistance properties and thus needs proper surface modification to sustain under severe industrial applications. Cobalt-based Stellite 6, a suitable coating for such applications, contains 4–5 % of tungsten that provides solid solution strengthening to the cobalt-based matrix, due to which it shows good wear resistance in abnormal working conditions. Stellite 6 is dominated by face-centered cubic (FCC) and hexagonal close packed (HCP) cobalt along with different carbide phases such as M7C3, M23C6, MC and M6C where M is Cr, W, Mo, Co and Fe. Weld deposited cobalt-based Stellite 6 coating on SS316L substrate, contains FCC structure as primary phases. Pure cobalt contains a stable HCP phase at temperature below 417 °C and FCC phase at and above 417 °C up to melting point of pure cobalt i.e., 1495 °C. Under the frictional stresses caused during wear test, impact more on FCC cobalt than HCP cobalt due to the high slip system of FCC. Because of this, FCC cobalt underwent through high wear losses compared to HCP cobalt in cobalt-based coating. Present study revealed that, high wear losses are seen in samples where FCC cobalt phases are dominant. The observed mechanism by SEM shows abrasive wear in which material removal takes place by ploughing, micro cutting and indentation. The targeted industrial applications where such wear losses are supposed to happen includes slurry transportation applications such as pipes, sea engineering components, submersible pumps, control valves.

Microstructure and wear-resistant behaviors of Al2O3-TiO2 reinforced Ni-based composite coating plasma-sprayed on 6061 aluminum alloy

Aluminium alloy is a widely used lightweight alloy in automobile and rail vehicle components, especially in parts such as brake pads and wheels, which require high wear resistance. Herein, to improve the wear resistance of aluminium alloys, Al2O3–13%TiO2 (AT13) reinforced Ni-based composite coatings were prepared by plasma spraying on 6061 aluminium alloy. The impact of AT13 content and heat treatment on the microstructure and wear resistance of Ni-based alloy coatings was systematically investigated. From our analysis, it was demonstrated that, in comparison to the substrate, the average micro-hardness of the composite coating with 10 %AT13 increased by more than 11 times, with a high value of 1250.81 HV0.2. Moreover, the average friction coefficient and wear rate reduced by 66 % and four orders of magnitude, with low values of 0.17 and 8.99 × 10−7 mm3(N−1∙m−1), respectively, which indicated a significant enhancement in wear resistance. In addition, after heat treatment at 450 °C for 2 h, the micro-hardness of the composite coatings was improved, and the wear rate further decreased. This effect could be attributed to the encapsulation of the hard ceramic particles in the nickel-based alloy, which may suppress the dislocation motion in the composite coating. This study provides valuable insights into enhancing the wear resistance of metal-based alloy coatings with ceramic composite coatings.

Effect of temperature on the tribological behavior of additively manufactured tool materials in reciprocating sliding against cemented carbide

Additive manufacturing (AM) of ferrous alloys has achieved a technological maturity level that allows for the production of high-performance steel components. Among these alloys, tool steels and maraging steels can be used in die manufacturing for different hot forming processes as both materials have good mechanical properties and thermal stability. In recent years, several works have successfully produced these alloys through selective laser melting, focusing on the optimization and characterization of their microstructure and mechanical properties. However, few studies look into the tribological aspects of these newly produced materials and even fewer consider high temperature friction and wear performance. Therefore, there is a need to understand the high temperature tribological response of tool materials produced by additive manufacturing. In this context, the aim of this work is to investigate the tribological behavior of a tool steel and a maraging steel, both produced by selective laser melting, at different elevated temperatures. A conventionally produced tool steel was used as reference. A reciprocating sliding tribometer was used to perform tests at 40 °C, 200 °C and 400 °C. The counter-body was a WC-Co cemented carbide. Friction and wear of the AM tool steel and reference tool steel were very similar, thus no signs of the AM route having an impact on the tribological behavior were observed. Both tool steels showed reduced wear volume with increasing temperature, while the opposite was observed for their respective WC-Co counter-bodies. Higher temperature also resulted in increased amount of W transferred onto the tool steel wear scars. AM maraging steel showed higher and more unstable friction level, as well as a much larger wear volume at all temperatures; material transfer onto WC-Co was observed at certain temperatures. Overall, tribolayer formation (or lack thereof) was the dominant aspect in the tribological responses.

Influence of tantalum addition on the microstructure and wear resistance properties of NiCuBSi/65WC composite coatings

Nickel-based tungsten carbide composite coatings are extensively utilized on various wear-resistant workpiece surfaces due to their exceptional properties, including high hardness and wear resistance. However, as the WC content increases, uneven structure and susceptibility to cracking of the coating during the forming process are enhanced, thereby impacting its service performance. To address these issues, NiCuBSi/65WC composite coatings with varying tantalum (Ta) contents were fabricated on 42CrMo steel substrates by laser cladding. The influence mechanism of Ta content on the microstructure and wear resistance of the coatings was investigated. The results demonstrate that the addition of tantalum promotes the formation of reinforcement phases such as TaC and W2C in the coating. Moreover, with increased Ta content, the edge of WC particle reaction layers in the coating gradually transforms from sawtooth to shorter rod-shaped morphology. Additionally, as the Ta content increases, the dissolution degree of WC particles rises, thereby facilitating the formation of TaC and W2C compound carbide. This leads to an enhancement in both the quantity and uniform distribution of carbide reinforced phases within the coating, resulting in an increase in average coating hardness from 482.4 HV0.2 to 580.1 HV0.2. When the Ta content reaches 7 wt% in particular, no cracks are observed on the coating surface, and a uniform distribution of carbides is achieved. The relative wear resistance of NiCuBSi/65WC coating with 7 wt% Ta is approximately 2.36 times higher than that without Ta.

Numerical analysis on lubrication failure of main bearings with lemon-shaped bearing shells in high-power diesel engine

The lubrication status of crankshaft main bearings significantly affects the stability and reliability of diesel engine operation. This paper primarily investigates the severe failure of main bearings during developing an industrial high-power 6 V diesel engine and analyzes the causes of bearing failure. Main bearings using lemon-shaped bearing shells exhibited failure after a short period of operation. Based on the multi-body dynamics model, average Reynolds equation, and contact model, a lubrication model for the main bearings was established, and the lubrication characteristics of each main bearing were simulated. The research shows that the abrupt peaks of the lemon-shaped bearing shells on the first and second main bearings are located within the area where the bearings suffer from burst pressure, resulting in additional hydrodynamic pressure and asperity contact pressure on the bearing surfaces. This makes the bearing surface prone to wear and high temperature, which are the primary causes of bearing failure. Under the operating conditions, surface damage of the bearings leads to particle abrasion and high temperature. Subsequently, the lubricating oil gradually deteriorates with the combined action of high temperature and wear particles, causing the main bearings to blacken and adhesive wear.

Biomimetic Design of Soil-Engaging Components: A Review.

Soil-engaging components play a critical role in agricultural production and engineering construction. However, the soil-engaging components directly interacting with the soil often suffer from the problems of high resistance, adhesion, and wear, which significantly reduce the efficiency and quality of soil operations. A large number of featured studies on the design of soil-engaging components have been carried out while applying the principles of bionics extensively, and significant research results have been achieved. This review conducts a comprehensive literature survey on the application of biomimetics in the design of soil-engaging components. The focus is on performance optimization in regard to the following three aspects: draught reduction, anti-adhesion, and wear resistance. The mechanisms of various biomimetic soil-engaging components are systematically explained. Based on the literature analysis and biomimetic research, future trends in the development of biomimetic soil-engaging components are discussed from both the mechanism and application perspectives. This research is expected to provide new insights and inspiration for addressing related scientific and engineering challenges.

Fretting fatigue crack initiation and propagation behaviours of Ti6Al4V alloy coated by functionally graded material

Fretting fatigue pertains to the behaviour of engineering components undergoing cyclic loading while in contact with each other. This intricate contact-related phenomenon often results in premature failure compared to conventional fatigue issues. Moreover, when these components operate in high-temperature atmospheres and experience high wear conditions, such as the heat transfer tubes in the nuclear reactor, the application of Functionally Graded Material (FGM) coatings becomes essential. Consequently, it is imperative to investigate how FGM coatings influence the initiation and propagation behaviour of fretting fatigue cracks. This paper employs the Critical Plane (CP) method to calculate the damage parameter. Additionally, Linear Elastic Fracture Mechanics (LEFM), specifically the Extended Maximum Tangential Stress (E-MTS) criterion, is utilized to examine how FGM coatings affect the paths of fatigue crack propagation in the presence of fretting conditions. Meanwhile, due to the unavailability of material properties of FGM coatings, the damage parameter and stress intensity factors are utilized to indirectly assess the effect of FGM coatings on crack initiation and propagation lifetimes. The FGM coating significantly influences tangential stress, thereby affecting the length of the stick zone, while having minimal impact on the distribution of normal stress along the contact surface. Furthermore, it is observed that adjusting the variation in composition of FGM coatings and the elastic modulus of the first FGM coating layer provides a potential technique for enhancing both crack initiation and propagation lifetimes.

The development of B/Cr co-doped DLC coating by FCVA deposition system and its tribological properties at 300 °C

The diamond-like carbon (DLC) coating prepared using filtered cathodic arc deposition (FCVA) lost its promising wear resistance under high temperatures. Element-doped DLC coatings have been investigated to suppress carbon oxidation reaction and subsequently enhance the wear resistance in high-temperature environments. Previous research clarified the excellent tribological properties of boron-doped DLC (B-DLC) but identified challenge such as arc discharge extinguishment and coating declamation (under high-temperature friction test). In this study, the introduction of Argon gas (10 sccm) during the deposition process stabilized stable arc discharge, resulting in high hardness and deposition rate. Moreover, a chromium interlayer and varying concentration of Cr dopant (0.5 %, 1.0 %, 3.0 % at.) were added to B-DLC to develop a stable, co-doped DLC with low friction and high wear resistance. Raman spectroscopy and nano-indentation revealed an increase in the disordered carbon structure and reduction in hardness and Young's Modulus with Cr doping. Macroscopic ball-on-disk friction test, showed 1 % Cr-doped B-DLC (a-C:B:Cr1) coating exhibited super low friction (avg. coefficient 0.02) and a low specific wear rate (<5.0 × 10−6 mm3/Nm). Raman spectroscopy indicated that the transferred graphite-like tribo-film onto the surface of Si3N4 counterparts contributed to stable low friction. Additionally, XPS analysis on the DLC coatings' wear track suggested the rich BB bond might contribute to its high wear resistance. This successful improvement on element-doped DLC prepared by FCVA provided valuable insights for further exploration of DLC coating applied to various working situations.

Variation in wear scar penetration depths due to impact angle on the erosion wear of advanced aluminum matrix nanocomposites

In present study, developing (Al-Fe-Si) materials with high wear and erosion resistance for aerospace components, such as wing skin and fuselage sections, presents a significant challenge for researchers. This study delves into the reinforcement effects of TiC in aluminum composites, produced via ultrasonic-assisted stir casting. The focus lies on exploring the UASC technique to create composites with varied TiC weight percentages (0 %, 2 %, 4 %, and 6 % by weight) and evaluating their erosion resistance. Experiments varied erodent particle impact angle, velocity, and discharge rate, alongside impingement angles, and maintaining a constant velocity of 151 m/s for 10-minute durations, using solid particles averaging 201 µm in size. Increasing TiC content improved erosion resistance. Optical profilometry revealed a −131 µm maximum wear scar depth at a 45° impingement angle, with significantly higher erosion wear compared to other angles. These findings offer valuable insights for enhancing mechanical system design and durability. Eroded surface failure analysis utilized FE-SEM images to examine composites impacted by erodent forces.

Alloy modification and ultrasonic-assisted milling of wear-resistant alloys with defined surfaces

The reduction of CO2 emissions is closely linked to the development of highly efficient and economical steel components in plant and process engineering. To withstand the high combined corrosive, tribological, thermal, and mechanical stresses, wear-resistant coatings tailored to the application and steel grade are used. In addition to the increasing demand to substitute conventional cobalt alloys with nickel alloys, there is also a growing need for defined or functional surfaces of high integrity. Due to high tool wear, milling operations required to produce the complex geometries of the components are often not economically feasible for SMEs. By means of alloy modification of the filler metals for nickel-based plasma build-up welded wear-resistant coatings and by the use of innovative ultrasonic-assisted milling processes more favourable machinability shall be achieved without reducing the wear protection potential. In this paper, the influence of the microstructure and precipitation morphology adjusted by means of alloy modification on the machinability is investigated. This is done based on a wear protection alloy NiCrMoSiFeB (trade name: Colmonoy 56 PTA) typically used for screw machines, which substitutes conventional CoCr alloys (Stellite). Metallurgical investigations and in-situ measurements of occurring process forces and temperatures at the tool cutting edge during milling as well as subsequent investigations of tool wear and surface integrity allow a detailed analysis and correlation between microstructural properties and machinability. For the cast samples, a clear change in the microstructure and hardness can be seen through the addition of Al, Ti, or Nb. These differences lead to an improvement in the machining process for Nb. Al and Ti cause long-needled or star-shaped precipitations and hardness increases, which lead to higher cutting forces and increased tool wear.

Cloud maps highlighting dynamic characteristics of surface signal to improve time-varying wear evaluation accuracy

This paper proposes a high accuracy time-varying wear evolution method with cloud maps highlighting dynamic characteristics of surface signal. Firstly, the cloud map method is established by arrangement of measured data, thus time-varying wear evolution process is visualized on a series of plane figures for preliminary qualitative analysis. Then, high accuracy recognition of time-varying wear states is realized by cloud map shape parameters, including kurtosis and 1-D kernel density function highlighting distribution information of surface signal. The relative recognition degree by cloud map shape parameters are higher than those of friction coefficient, Root-Mean-Square (RMS) deviation and fractal dimension. Finally, high accuracy time-varying wear life prediction is realized by cloud map size growing speed highlighting waviness information of surface signal. The relative prediction error is reduced from more than 20% to less than 10% compared with friction coefficient and roughness.