Wear Tests Research Articles

Wear behaviour analysis of thermo-mechanically processed AA7075 and AA7075/SiC/Graphite composite

The current work focuses on investigating the tribological performance of AA7075 alloy and AA7075 hybrid composite with SiC and graphite reinforcements of 2 and 0.5 wt percentages, respectively. The alloy and hybrid composite are fabricated through stir casting and thermo-mechanically processed through hot rolling routes. Dry sliding wear characterization has been carried out using a pin-on-disc wear testing setup for alloy and composite under various processing conditions using experiments designed according to Taguchi's L9 orthogonal array. The technique for order preference by similarity to ideal solution (TOPSIS) method has been adopted to achieve a single multi-response index (MRI) considering the minimization of multiple objective functions for specific wear rate (SWR) and coefficient of friction (COF). The analysis of variance (ANOVA) results of the MRI indicated that sample processing condition and load were the most significant parameters. The wear mechanism at different experimental conditions was studied using Scanning electron microscope (SEM) micrographs, energy dispersive spectroscopy analysis and 3D surface profile of wear track. The AA7075 composites are found to be comparatively good in all experimental conditions compared to the base alloy due to load-bearing SiC particles and solid lubricant graphite as reinforcing elements. The mechanically mixed layer (MML) formation in hybrid composites helped achieve good tribological properties. The AA7075 alloy and hybrid composites cross rolled at 350 °C yielded better results than other samples. The wear mechanism was abrasive and adhesive at low temperature and low load conditions in both alloy and hybrid composites. Whereas, at higher temperatures and high loads oxidative wear mechanism with delamination was prevalent. The transition of SWR from mild to severe value occurs at 250 °C in all experimental cases. The specific wear rate was improved by 85.64 % between worst and best conditions, i.e., annealed alloy and cross rolled composite.

Dual surface-modification by oleic acid and epoxy-based silane coupling agent providing cerium oxide nanoparticles as additive in pentaerythritol oleate with improved high-temperature adsorption performance and tribological properties

An epoxy-based silane coupling agent (KH560) was grafted onto the surface of oleic acid-modified cerium oxide (CeO2-OA) nanoparticles in order to improve the competitive adsorption ability of the anti-wear additives in ester oils and simultaneously hinder the additive desorption owing to thermal disturbance under high-temperature condition. The as-prepared oleic acid-epoxy silane co-modified cerium oxide (CeO2-OA/E) nanoparticles were characterized. The effect of temperature on the adsorption behavior of trityl phosphate (TCP, a commercial high-temperature antifriction agent), CeO2-OA and CeO2-OA/E in PETO was studied using a dissipative quartz microbalance. Their tribological properties as the additives in pentaerythritol oleate (PETO), a polar ester base oil, were evaluated with a four-ball machine and a ball-on-block friction and wear tester; and their tribomechanism was explored with respect to their adsorption behavior on rubbed steel surfaces at elevated temperatures. It was found that the secondary surface-capping of CeO2-OA by the KH560 silane coupling agent resulted in great increases in the surface potential (from 54 mV to 396 mV) and thermal stability as well (the thermal decomposition temperature rose from 185 °C to 254 °C). Among the tesetd lubricant additives, CeO2-OA/E exhibited the highest adsorption mass, because of the highest surface potential the chemisorption ascribed to the epoxy group of the silane coupling agent. Particularly, CeO2-OA/E added in PETO exhibited better friction reduction and anti-wear properties at 150 °C than CeO2-OA and TCP, because CeO2-OA/E added in PETO formed tribofilm composed of CeO2 and SiO2 with excellent thermal stability as well as friction-reduction and antiwear effects through stable chemical adsorption and tribochemical reaction at elevated temperatures.

Preparation and tribological properties of PAI/PTFE@Mg-Al LDH polymer-based solid self-lubricating materials

PAI/PTFE composites with 1 %, 2 %, 3 %, 4 % and 5 % of Magnesium aluminum hydrotalcite (Mg-Al LDH) particles were prepared by DC electric field-assisted hot-pressing sintering. The friction and wear properties of the composites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), water contact angle and UMT-5 friction and wear tests. The effect of the amount of Mg-Al LDH particles added on the physical properties and friction and wear properties of the composites were analyzed. Experimental results showed that the friction and wear properties of PAI/PTFE composite films can be improved by adding appropriate Mg-Al LDH particles. Among them, The PAI/PTFE polymer based solid lubrication containing 3 % Mg-Al LDH has the best friction coefficient and wear amount, the average friction coefficient is 0.0962 and the wear extent is 1.47×10−5 g. The improved tribological properties of the composite films are mainly due to the excellent mechanical properties of Mg-Al LDH and the good lubrication properties of PTFE.

Erosion wear of the multilayered high velocity oxy‐fuel ceramic coatings on aluminum alloy composite substrate

AbstractHigh velocity oxyfuel coatings have been sprayed on aluminium (Al) alloy composites substrate with varying coating thickness and tested for their wear behavior. The density and micro‐ hardness of the coatings found to increase with increase in coating thickness. The air erosion wear test has been conducted using quartz sand of size up to 75 μm as erodent. The steady state experiments indicate that the greatest specific erosion rate is at 60° and minimum at 30°. Due to the presence of interlayer, specific erosion rate decreases with the increase in the thickness of the coatings. Surface topography of the eroded samples indicate a decrease in surface roughness with increase in impact velocity. Thereafter, Taguchi (L16) orthogonal array has been utilized in order to optimize the input parameters. Analysis of variance has been applied to determine the contribution of individual control factors. The results from Taguchi experiments and analysis of variance find the order of dominance of control factors and their individual contribution as: velocity (47.31 %) > coating thickness (29.94 %) > angle (13.26 %) > erodent feed rate (7.65 %). Coatings have exhibited a semiductile wear behavior.

Enhancing tribological performance of high‐density polyethylene polymer with diamond‐like carbon coating and mollusk shells filler

AbstractThis study explores the tribological properties of mollusk‐shell‐high‐density polyethylene (MS‐HDPE) biocomposites and diamond‐like carbon (DLC)‐coated metal beads as potential substitutes for hip joint prostheses. HDPE biocomposites with 0, 5, and 10 wt% of MS were developed using hot compression molding. Coatings included pure DLC, DLC‐Si, and DLC W:H. Wear tests on a ball‐on‐disk tribometer examined friction and wear rates against coated and uncoated balls, along with wear morphology. MS‐HDPE demonstrated superior tribological performance against DLC, achieving a 67% reduction in specific wear rate compared to pure HDPE. The study suggests that 5 wt% MS‐HDPE coupled with a DLC‐coated counterpart coating could be a promising combination for orthopedic applications, presenting a potential solution to metal corrosion and wear debris issues in orthopedic implants.Highlights Tested coatings: DLC, DLC‐Si, and DLC W:H. Biocomposite wear versus coated balls. DLC coating improves wear with shell fillers. Mollusk shell strengthens biocomposites. Reduced wear rate by 63% and friction by 77%.

Improvement of AISI 316L laser cladding properties by high-frequency vibration process

In the present paper, a unique laser cladding-assisted high-frequency vibration device was applied to prepare the AISI 316L cladding layer by laser cladding on the surface of the AISI 316L stainless steel substrate. The macroscopic morphology, microstructure, microhardness, and wear resistance of the cladding layer were analyzed by optical microscope, scanning electron microscope, Vickers microhardness tester, friction and wear tester, and three-dimensional optical profiler. The laser cladding-assisted high-frequency vibration device uses a high-frequency oscillator with a fixed frequency (20 KHz) to transfer vibration energy through the probe in contact with the substrate and close to the molten pool. This paper explores the effect of different laser powers on the dilution rate of the cladding layer, compares and observes the cross-sectional morphology and microstructure of the cladding layer with and without high-frequency vibration, and analyzes the reasons for the different results.

Development of a Cost-Effective Twin-Disc Test Rig for Railway Wear Simulation

Maintenance due to the replacement of damaged wheels and rails due to rolling contact fatigue (RCF) and wear has been found to be the major problem to rail operating companies. This problem tends to lead to unavailability of railway networks. To solve this problem, costly wear simulators are developed to predict the wear behaviour of the rails and wheels to improve the preventive maintenance in pursuit of operational efficiency. Therefore, more studies that simulate a combination of rolling and sliding wear, together with RCF, are required, specifically for the Southern African, where good and cost-effective rail wear simulators are not readily available. The problem with wear and RCF simulators is high production costs, so this work aims to solve this problem by developing a cost-effective wear test rig that is capable of simulating RCF, sliding and rolling wear as experienced by the train wheel while moving along railway tracks. For this work, it was decided that twin-disc concept would be used, since literature clearly shown that the method was able to simulate the three damage mechanisms mentioned. The developed twin-disc wear simulator was able to simulate both rolling and sliding wear and parameters including contact load and slip ratio could be changed with ease so to simulate the actual contact conditions between the wheel and rail. Outputs such as coefficient of friction and wheel disc temperature were obtained. The results showed that the severity of wear is heavily dependent on slip ratio i.e., increased with slip ratio, with both coefficient of friction and wear rate increasing with slip ratio.

Achieving enhanced strength-ductility and wear resistance in directed energy deposited super duplex stainless steel via inoculating NbN particles

In wire-based directed energy deposition (DED), super duplex stainless steel (SDSS) typically encounters issues including coarse grains, a contradictory relationship between strength and ductility, and inferior wear resistance properties. Herein, we report the introduction of micron-sized NbN particles into DEDed SDSS to achieve an optimized combination of fine microstructure, high strength, impressively larger ductility and better wear resistance. During the DED process, NbN inoculant dissolves and re-precipitates, forming fine NbN and σ particles around 100 nm in size. These NbN particles act as nucleation sites for equiaxed grains, refining both ferrite and austenite. In addition, Nb and N elements left from NbN dissolution enhance the solution strengthening effect. These factors collectively boost hardness and strength in DEDed SDSS. Furthermore, the high Nb level in DEDed SDSS facilitates a dense Cr2O3 layer formation on the specimen surface during wear tests, enhancing wear resistance. Increased Nb and N also lower stacking fault energy (SFE) of SDSS austenite, promoting the occurrence of deformation twinning, and the improvement of work hardening and ductility during plastic deformation. This work shows the great potential of wire-arc DED technology to fabricate SDSS with unique microstructures, excellent wear resistance, and an exceptional combination of strength and ductility for practical applications.

Specific Erosion Resistance Behaviour of Cold Forged and Angular Extruded Aluminium.

Aluminium finds wide application in mechanical engineering due to its low density and corrosion resistance. In this research, aluminium was subjected to two different metal forming technologies-cold forging (upsetting) and equal channel angular pressing (ECAP)-to obtain improvement in its exploitation properties. Parallel to changing mechanical properties by using these two processes, there was a change in the microstructure of the material. The resulting microstructures were examined using an optical microscope. A different treated aluminium was subjected to erosion wear in various time intervals. Wear testing was conducted for two different impingement angles causing abrasive wear and impact wear. The erosion mechanisms were examined by scanning electron microscopy. These results showed that there is no statistically significant difference in erosion wear for different states at the same impingement angle. However, the difference is noticeable at different wear angles. The significance of the difference in wear of the samples treated with the forging and ECAP techniques was validated by statistical analysis with tests of different sensitivities. The results of the t-test showed that ECAPed samples present a statistically significant difference in the loss of mass due to variations in erosion angle during the 30, 45, and 60 min wearing. A substantial difference in the change in sample mass is also visible for the forged state worn for 60 min.

Optimization of Cyanide-Free Composite Electrodeposition Based on π-π Interactions Preparation of Silver-Graphene Composite Coatings for Electrical Contact Materials.

With the rapid development of industrial automation and power electronics, the requirements for electrical contact materials are increasing. However, traditional electrical contact materials encountered significant bottlenecks in terms of performance enhancement and production environmental friendliness. Therefore, this paper proposes a new material design idea that utilizes π-π interactions between graphene and compounds with conjugated structures in order to achieve uniform dispersion of graphene in the metal matrix and thus enhance the performance of composites. Based on this design idea, we used nicotinic acid, which has a conjugated structure and is safe, as the complexing agent, and successfully prepared high-quality silver-graphene (Ag-G) composite coatings with graphene uniformly dispersed in the metal matrix on copper substrates by composite electrodeposition technique. Subsequently, the mechanical properties of composite coatings were investigated by hardness test and X-ray diffractometer, and the tribological properties of the composite coatings and the comprehensive performance under the current carrying conditions were systematically evaluated by using friction and wear tester and load key life tester. The results show that the Ag-G composite coatings have significant advantages in mechanical, tribological, and current carrying conditions. This result not only verifies the feasibility of the design idea of the material, but also provides a new direction for the research and development of electrical contact materials.

Evaluation of wear and friction properties of graphite modified Lubri polylactic acid with various infill fabricated by additive manufacturing techniques

AbstractThree‐dimension (3D) printing technology, also known as additive manufacturing, is a manufacturing technology that creates three‐dimensional objects by depositing material layer by layer, as opposed to subtractive manufacturing methods. However, the newness of the technology brings with it many unknowns. In particular, the raw materials used are constantly increasing. For this reason, testing each raw material used in many aspects and to determine the optimum production conditions is important for the wide use of 3D printing technology. These optimal conditions may be the parameters used to produce a material, and sometimes they can appear as a new material. In addition, the production of new materials with varying production parameters is fundamental research topic that requires comprehensive study. For all these purposes, in this study, a new material type known as Lubri PLA (LPLA) was selected and produced in different filling types and subjected to a series of friction and wear tests. Thus, it is aimed to determine the tribological properties of the material. Additionally, samples were produced in ten different infill types (grid, lines, triangels, hexagon, cubic, octal, zigzag, diagonal, diagonal 3D and gyroid) to show the effect of filler type on friction and wear behavior. These filler types were used for both PLA and Lubri PLA materials and a total of twenty samples were produced. Thereby, it is aimed to conduct a comprehensive study showing the effect of both material difference and filling type on friction‐wear behavior. Diameter deviations, hardness deviations, friction coefficient, temperature, specific wear rates (SWr), and vibration were selected as output parameters. According to the analysis of the test results, the best result in terms of material structure was given by Lubri PLA, while the best result in terms of filling type was obtained with Diagonal 3D filling type. In addition, the lowest vibration level was obtained in the LP‐Diagonal 3D sample with 0.041 mm/s2, while the highest vibration level was obtained in the P‐Grid sample with 1.756 mm/s2.Highlights LPLA closed to nominal value in diameter and hardness deviations Addition of graphite nanoparticle increased the dimensional accuracy Diagonal 3D infill type Lubri PLA composites showed the superior performance Graphite modified Lubri PLA composites demonstrated superior performance

The Influence of Cryogenic Treatment on the Tribological Properties of Tungsten Carbide

Improvement in wear resistance and hardness of cutting tool material is one of the most critical challenges in machining operations. This issue can be addressed by enhancing wear resistance and hardness through cryogenic treatment of tungsten carbide. This study investigates the effect of different soaking periods during cryogenic treatment on commercially available tungsten carbide. Experiments were conducted at a temperature of 88K with varying soaking periods of 8 hours, 20 hours, 24 hours, and 30 hours. To quantify and confirm the impact of different soaking periods on hardness and wear resistance, Rockwell hardness measurements and weight loss during wear tests were performed. The results indicate a significant decrease in weight loss for the sample soaked for 8 hours compared to other soaking periods, although there was no change in bulk hardness. The reduced weight loss during the sliding wear test suggests that cryogenically treated tungsten carbide exhibits improved wear resistance due to an increased population density of carbides. Microstructural analysis of the worn surface reveals the mechanism behind the enhanced mechanical properties. Key Words: Cryogenics, dct, sct, microstructure, soaking period, tool life.

Effect of process parameters on mechanical and tribological characteristics of FDM printed glass fiber reinforced PLA composites

PurposeAdditive manufacturing of polymer composites is a transformative technology that leverages the benefits of both composite material and 3D printing to produce highly customizable, lightweight and efficient composites for a wide range of applications.Design/methodology/approachIn this research work, glass fiber-reinforced polylactic acid (PLA) filament is used to print the specimen via fusion deposition modeling process. The process parameters such as infill densities (40%, 50% and 60%) and raster angle/orientations (0°, 45° and 90°) are varied, and the specimens for tensile, flexural, impact, hardness and wear testing are prepared as per their respective ASTM standards.FindingsThe results revealed that with an increase in infill density, the mechanical properties of glass fiber-PLA specimens increase progressively. Optimal tensile properties and flexural properties are obtained at 0° and 90° raster angle orientations and 60% infill density. Minimum wear rate is achieved at 0° raster angle orientation and it increases at 45° and 90° raster angle orientations.Originality/valueUsing SEM, the microscopic analysis of the fractured specimen was analyzed to study the interface between the fibers and matrix and it indicates the presence of good adhesion between the layers at 60% infill density and 0° print orientation.

Impact and tangential composite fretting wear of Zr-4 alloy tubes under random loading conditions

The fuel rod casing tube is a crucial component in pressurized water reactor (PWR) nuclear power plants. Flow-induced vibrations in the circulating water can result in complex alternating fretting wear between the casing tube and the positioning lattice frame. Existing research on fretting wear has primarily focused on unidirectional wear, with limited investigation into composite fretting wear under complex working conditions. This study conducted impact and tangential composite fretting wear tests on Zr-4 alloy tubes under varying constant and random impact loads to examine fretting wear behavior. The findings show that the peak friction coefficients in the impact and tangential composite fretting wear tests were consistent across the three constant load conditions, with higher peak friction coefficients observed under random load conditions and a longer time required to reach these peaks during micromotion tests. Comparative analysis revealed that random impact and tangential composite fretting wear caused the most severe damage. Under constant load conditions, wear damage became more severe with increasing load, transitioning from oxidized and adhesive wear to a peeling layer as the load intensified in the impact and tangential composite fretting wear tests.

Enhancement of wear and corrosion resistance of pulsed electrodeposited Ni–Mo amorphous/nanocrystalline coatings by heat treatment

In this study, Ni–Mo coatings with various sodium molybdate concentrations were designed and successfully electrodeposited. The effects of treatment with different temperatures (200 °C,400 °C, 600 °C) on the microstructure and properties of the best-performing coating (4 g/L) were investigated. The surface morphologies, elemental content, and phase structure of the prepared coatings were obtained and analyzed by SEM, EDS, XRD, WFI and TEM. The Ni–Mo coating after heat treatment at 400 °C formed the compact and uniform amorphous/nanocrystalline coating. As shown by the electrochemical and wear test. Heat treatment at 400 °C improved the coating properties, and the corrosion current density was decreased by 66 % to 6.2532 × 10−7 A/cm2. The wear rate reduced from 8.3 × 10−4 mm3/N·m to 3.6 × 10−4 mm3/N·m, and the average friction coefficient minimized to 0.079. Additionally, compared with the as-deposited coating, the microhardness reaches the maximum (1048 HV). The formation of the oxide layer and the intermetallic compound MoNi on the surface of the coating plays a carrying and hindering role, thus the surface of the coating shows excellent wear and corrosion resistance. In addition, the corrosion inhibition mechanism during the heat treatment of Ni–Mo coatings was further explored.

Improved wear and corrosion protection of Ni–P alloy coating by an electrodeposited Ni–Co–P alloy coating

To improve the comprehensive protection performances of steel C1045 surface, the Ni–Co–P alloy coatings with varying CoSO4·7 H2O concentration (0, 10, 20, 30, 40, 50, 60 and 70 g·L–1) were successfully prepared by an electrodeposition technique on a steel C1045 surface. The effect of the addition of CoSO4·7 H2O in the plating solution on the surface microstructure, elemental composition, crystallite size, microhardness, wear and corrosion resistance of the Ni–Co–P alloy coatings were analyzed by using a scanning electron microscope, an energy dispersive spectroscopy, an X-ray diffraction, a microhardness tester, a friction wear tester and an electrochemical workstation, respectively. The results indicated that the Ni–Co–P alloy coating exhibited a flatter morphology, compact microstructure and more excellent properties compared with Ni–P alloy coating, and the addition and variation of CoSO4·7 H2O in the plating solution had significant effects on the surface microstructure and comprehensive protection performances Ni–Co–P alloy coating. Notably, when the mass concentration of CoSO4·7 H2O in the plating solution was 50 g·L–1, the Ni–Co–P alloy coating had the highest content of Co element (22.67 wt·%), smallest crystallite size (20.41 nm) and highest microhardness (716.2 HV0.1). Furthermore, its wear resistance and corrosion resistance were considerably improved compared to that of the Ni–P alloy coating. The minimum average dynamic friction coefficient, wear scar width and depth of Ni–Co–P alloy coating at 50 g·L–1 were 0.47±0.02, 450.9 µm and 14.1 µm, respectively. The corrosion current density (Icorr) of Ni–Co–P alloy coating was the smallest (0.68 µA·cm–2), the corrosion rate (Rcorr) was slowest (8.25 µm·year–1), and the polarization resistance (Rp) of the Ni–Co–P alloy coating was highest (29.83 kΩ·cm2). The corrosion resistance of Ni–Co–P alloy coating was best.

Achieving ultra-low wear of Ti6Al4V alloy by introducing a sinusoidal nitriding layer via nanosecond pulsed laser irradiation

Introducing wear-resistant layers or constructing microtextures is normally employed to improve the wear resistance of materials. However, single role of the wear-resistant layer or microtexture still could not effectively address the wear issue of titanium alloys. In this study, a sinusoidal nitriding layer is directly fabricated on the Ti6Al4V surface by one-step laser irradiation. Chemical composition and microstructure analysis indicate that the nitriding layer contains TiN and α-Ti phases, and it is metallurgically bonded to the heat-affected zone. Friction wear tests show a 96.9 % reduction in wear rate with dry sliding and 99.6 % with oil lubrication, without exhibiting groove orientation dependence. The wear mechanism is discussed by scrutinizing the morphology of the wear scars and their corresponding cross-sections.

Rotary barrel tumbling as a method of surface preparation for pin-on-disc wear testing samples

Surface preparation is essential to ensure sample homogeneity in terms of surface roughness and mechanical properties, as these factors can significantly affect wear behavior and test repeatability. Although conventional semi-automatic and automatic grinding and polishing processes are efficient and well established, limitations arise for the preparation of large numbers of samples of a hard material such as high-carbon steel, including issues with sample geometry, the need for on-demand sample holders, cost-related limitations, and even considerable human workload and expertise. This study aims to evaluate the use of rotary barrel tumbling—a polishing method that relies on the sliding of abrasive media over the samples’ surface inside a rotating barrel—as an alternative method to prepare the surface of wheel and rail steel samples for pin-on-disc wear testing. A 4-stage tumbling procedure was employed, using different compositions of tumbling media in each stage. Surface roughness and hardness were evaluated throughout the process via 2D and 3D profilometry, microhardness Vickers measurements, and optical microscopy. The proposed method resulted in significant reductions in the surface roughness and hardness of the samples, along with improved homogeneity between samples of different materials and within the same material. These findings suggest that rotary barrel tumbling is an effective alternative method for the surface preparation of pins and discs made of high-carbon steel, enhancing the samples’ suitability for subsequent wear tests.

Research on the evolution law of aggregate micro-texture during long-term wearing of asphalt pavement

The micro-texture of aggregates plays a very important role in anti-skid performance of asphalt pavement. Three kinds of aggregates, limestone, basalt and sandstone, were used to prepare asphalt mixture to study the evolution law of micro-texture of aggregates under long-term wear. One Third Scaled Model Mobile Load Simulator (MMLS) was used to conduct wear tests on asphalt mixtures under two working conditions: drying and water immersion. Laser confocal scanning microscopy (LCSM) was used to test and analyze the micro-texture evolution of the original aggregate, mixed aggregate, and accelerated loaded aggregate surfaces. The mechanism of texture evolution was analyzed based on the mineral composition, Vickers hardness, and micro-structure of the aggregate. The results show that wear can lead to varying degrees of polishing of the aggregate micro-texture, with limestone>basalt>sandstone, and the drying condition is more severe than the water immersion condition. The wear degree of the texture is closely related to the mineral composition and hardness of the aggregate. The more complex the mineral composition, the greater the hardness and hardness dispersion, the less likely the texture will be polished. The micro-texture indexes Ra and Rq have the highest correlation with anti-skid performance, and the relationship between them is obtained by fitting. Scanning electron microscopy (SEM) shows that the fine particles in sandstone are easy to fall off, which is conducive to the regeneration of texture, and is also the internal reason for its best anti-skid durability.

Qualitative surface roughness of lithium disilicate endo-crown for pulpotomized primary molars

Rehabilitation of pulpotomized primary molars with an appropriate restoration is essential for recovering function and safeguarding the durability of the treatment. This study aimed to assess and compare the surface roughness of stainless steel (ST) crowns, zirconia (ZR) crowns, fiberglass (FG) crowns, and lithium disilicate (LD) endo-crowns as a restoration for pulpotomized primary molars also, evaluating the surface roughness of their antagonists. Sixty pulpotomized primary mandibular first molars were used for qualitative surface roughness evaluation and divided into four groups (n = 15/group) according to the crown type (group-ST, group-ZR, group-FG, group-LD). While the other sixty sound, unprepared primary maxillary first molars were used for evaluation of their surface roughness against the tested crowns. Specimens’ preparation and cementation were carried out according to each crown type and manufacturer’s instructions. The surface roughness was done using a two-body wear test. The data were statistically analyzed. All tested crowns showed an increased change in surface roughness, except group-ZR, which had the least change in surface roughness after mechanical wear with no statistically significant difference(P = 0.681). All crown types significantly increased the surface roughness of their antagonists after mechanical wear, except group-ST which showed insignificant affection (p ≥ 0.05). Zirconia crowns and lithium disilicate endo-crowns had the least change in surface roughness compared to other groups while SSCs showed the least tooth loss in the antagonist enamel.