Dry Sliding Wear Tests Research Articles

OPTIMIZATION OF WEAR STUDIES ON LASER CLADDED AZ61 MAGNESIUM ALLOY WITH NANO-TITANIUM DIOXIDE USING GREY RELATIONAL ANALYSIS

Laser cladding (LC) is mostly employed to enhance the wear resistance of magnesium alloy substrates. Adding nanoparticles will further strengthen the tribo surface properties, making them suitable for applications requiring lightweight components. This work investigated a dry sliding wear analysis for the laser-cladded AZ61 magnesium alloy with TiO2 nanoparticles at different volume ratios through the LC method. The spatial dispersion of the TiO2 nanoparticles in the AZ61 magnesium alloy microstructure was analyzed using scanning electron microscopy (SEM). The reinforcement ratio, sliding speed, and normal load were selected to study the tribo performance of the cladded surface. Coefficient of friction (COF) and wear loss analyses were performed using a pin on the disc dry sliding wear test. The effect of dry sliding variables on reinforcement ratio was analyzed with an orthogonal array experimental design. Grey relational analysis (GRA) studied multiple wear test responses to reveal optimal conditions to decrease the wear and friction coefficient of the AZ61 laser cladded surface. The reinforcement percentage of nanoceramic TiO2 particles in the AZ61 alloy surface was the most significant factor, contributing 97.76%, followed by a contribution of 0.26% by sliding speed and a normal load of 1.82%, confirmed with the grey relational grade. Both SEM and GRA confirmed that the reinforcement ratio of 10% exhibited lower wear loss and friction coefficient. The revealed wear mechanism operating on the worn surface of laser-cladded AZ61 magnesium alloy was micro-grooving exerted by a counter surface at all sliding conditions. This study shows that the LC of magnesium alloys will be preferred in sliding seal and lightweight gear applications.

Mechanism Correlating Microstructure and Wear Behaviour of Ti-6Al-4V Plate Produced Using Selective Laser Melting

In the present study, a dry sliding wear test has been conducted to analyse the wear rate of Ti-6Al-4V alloy specimens which were fabricated using selective laser melting and conventional methods. Microstructure, micro- and nanohardness, and wear behaviour of selective laser melting specimens were investigated and compared with commercially available conventionally fabricated Ti-6Al-4V specimens. The mechanism correlating microstructure and wear behaviour of conventional and selective laser melting based Ti-6Al-4V specimens have been explained. The microhardness of the selective laser melting specimen was improved by around 22.4% over the specimen from the conventional method. The selective laser melting specimen showed broadened peaks and an increase in intensity height greater than that of the conventional specimen due to the presence of the martensite phase. The selective laser melting specimen possessed 41.4% higher nanohardness than that of the conventional specimen. The selective laser melting specimen had a 62.1% lower wear rate when compared to that of the conventional specimen. The selective laser melting specimen exhibited 62.7% less coefficient of friction than that of the conventional specimen at a 50 N load with 1.2 m/s sliding velocities. The finer needle-like microstructures of the specimen produced using the selective laser melting process had higher wear resistance, as it had higher hardness than the conventional specimen.

Characteristics of Hydroxyapatite-Modified Coatings Based on TiO2 Obtained by Plasma Electrolytic Oxidation and Electrophoretic Deposition

In order to modify the surface of light metals and alloys, plasma electrolytic oxidation (PEO) is a useful electrochemical technique. During the oxidation process, by applying a positive high voltage greater than the dielectric breakdown value of the oxide layer, the formation of a ceramic film onto the substrate material is enabled. The resulting surface presents hardness, chemical stability, biocompatibility, and increased corrosion wear resistance. The current study aims to investigate the corrosion resistance and tribological properties of PEO-modified coatings on titanium substrates produced by applying either direct or pulsed current in a silicate-alkaline electrolyte. In this way, a uniform TiO2 layer is formed, and subsequently, electrophoretic deposition of hydroxyapatite particles (HAP) is performed. The morpho-structural characteristics and chemical composition of the resulting coatings are investigated using scanning electron microscopy combined with energy dispersive spectroscopy analysis and X-ray diffraction. Dry sliding wear testing of the TiO2 and HAP-modified TiO2 coatings were carried out using a ball-on-disc configuration, while the corrosion resistance was electrochemically evaluated at 37 °C in a Ringer's solution. The corrosion rates of the investigated samples decreased significantly, up to two orders of magnitude, when the PEO treatment was applied, while the wear rate was 50% lower compared to the untreated titanium substrate.

Effect of cryogenic treatment on wear behavior of Sleipner cold work tool steel

Cryogenic treatment, also known as subzero heat treatment, is a cooling process that complements conventional heat treatment to improve the properties of metals. Unlike coatings, it is a one-time, inexpensive, permanent operation that affects the entire part. This method is mainly applied to tool steels used in mold making. In this study, the changes caused by the effects of shallow and deep cryogenic treatment on Sleipner cold work tool steel were investigated in terms of microhardness, microstructure, coefficient of friction (COF), and wear rate (WR). For this purpose, the test specimens were subjected to the cryogenic treatments performed at two different temperatures (−80 ºC for the shallow cryogenic treatment (SCT) and − 180 ºC for the deep cryogenic treatment (DCT)) and various retention times (12 h, 24 h for SCT and 12 h, 24 h, 36 h for DCT). Dry sliding wear tests were carried out under different loads (10 N and 20 N) and varying test durations (60, 120, and 240 min) at a constant sliding speed of 0.075 m/s. According to the microhardness results, it was determined that the cryogenic treatment increased the hardness by 6.53 %. According to the microstructure investigations, a more homogeneous structure was observed with the cryogenic treatment, and secondary carbide precipitations were detected. It was observed that the conventional heat-treated (CHT) sample gave the highest COF value with an average coefficient of friction of 0.63. The lowest COF value of 0.58 was observed in the DCT-12 sample. After the wear tests, the lowest wear rate value for both load values was obtained from the DCT-36 specimen.

A comparative analysis of the effect of laser surface treatment on the dry sliding wear behavior of ductile cast irons with different microstructures

In this study, the wear behavior of ferritic (GJS 400) and pearlitic (GJS 700) ductile cast iron (DCI) specimens after laser surface hardening were investigated comparatively. In general, multi-pass laser applications are inevitable in a laser surface treatment (LST) applied for surface hardening because the laser spot diameter is quite small compared to the applied surface area. This situation may cause a decrease in wear resistance due to residual stress formation because of the thermal gradient and softening effect due to the overlap ratio. In this study, a single-pass laser surface hardening (LSH) process with a laser pulse area of 20 × 5 mm2 compatible with the laser energy density (6.28 J/mm3) used in the literature, was applied to overcome these limitations. Thus, it is aimed to make it possible to evaluate the comparative analysis more reliably. After LSH processes, hardness values of DCI samples increased approximately 4.3 times compared to untreated ones due to the transformation hardening effect. In the microstructure of the laser-treated pearlitic DCI samples, martensite was present as the dominant phase in addition to a small amount of residual austenite. As for the ferritic DCI samples, the ledeburite and martensite phases were detected. Dry sliding wear tests were performed using different loads (5 N, 10 N) and sliding speeds (10 mm/s, 20 mm/s, 30 mm/s). As a result, the wear volume loss values of laser-treated ferritic and pearlitic DCI samples could be reduced by approximately 26.6% and 30.7%, respectively, compared to untreated ones. The COF values of the untreated samples increased with increasing load, while those of LSHed decreased. Severe plastic deformation and delamination were observed for untreated samples, while mild plastic deformation and micro-grooves were observed for samples with LSHed.

Experimental optimization of tribological properties of aluminum bronze alloys made by the forging method

Aluminum bronze alloys produced by various methods are preferred materials in many fields of the industry due to their high wear resistance and good sliding properties. This study investigated the tribological properties of aluminum bronze alloys produced by forging from Cu, Al, Fe, and Mg elements. Dry sliding wear tests were carried out on a pin-on-disc wear device. Three tribological properties, wear, friction coefficient, and temperature of aluminum bronze alloys were investigated. Experimental studies were carried out for different loads, sliding speeds, and sliding ways. The factorial experiment design method was applied in the MINITprogram. A SEM visualized the samples microstructures to examine the material wear characteristics. As a result of the study, it was deter-mined that the applied load, sliding speed, and sliding way were effective parameters on the amount of wear and friction coefficient. The maximum amount of wear was 0.352 mg at 100 N load, 3 m/s sliding speed, and 3000 m sliding way conditions. The maximum temperature between materials under these conditions is 299 oC. The minimum amount of wear was obtained when 25 N load, 1 m/s sliding speed, and 1000 m sliding way were applied.

Synthesis and wear properties of near eutectic Al-Si-TiB2/Al2O3 hybrid composites

In metal matrix composites a metal/alloy is often combined with non-metallic/inter-metallic phases to produce a novel material possessing attractive engineering attributes of its own. AMCs or Aluminium matrix composites refer to the group of light weight, high performance, aluminium based material systems which are employed to meet the demand of automotive and aerospace sectors. The present study emphasises on casting of Al–11.8 wt% Si metal-matrix composites with the help of an exothermic reaction among the melt and halide salts (K2TiF6 and KBF4) to incorporate 2 and 3 wt% TiB2 in the base alloy matrix. Al2O3 particles (0.5, 1 and 2 wt%) were also mixed with these in-situ prepared composites to produce hybrid composites which were characterized using optical microscopy. Optical Emission Spectroscopy revealed some amount of silicon loss during casting. XRD analysis indicated the presence of Al2O3 and TiB2 in the cast composites. Hardness, density and dry sliding wear tests were carried out and analysed. The results of the present investigation revealed that the wear rate of the composites decreases when there is an increase in the TiB2 content but this behaviour is limited to 1 wt% reinforcement in case of Al2O3. Increasing load promoted wear rate. At higher sliding distances wear rate decreased though wear volume was more. Density values of the composites were found to increase with increasing amounts of reinforcements. Increasing Al2O3 up to 1 wt%, the hardness of the composites was found to increase. Further increase in Al2O3 to 2 wt% revealed lower hardness values of the composites due to agglomeration of the particles.

Investigations on wear behaviour of Al 6061-GNP metal matrix composites by using Taguchi L<SUB align="right">16 approach

High strength Al 6061 metal matrix composites with graphene in different weight percentages were fabricated through stir-casting followed by equal channel angular pressing. Dry sliding wear tests were conducted as per Taguchi-based L16 orthogonal array with control factors such as: 1) reinforcement (wt. %); 2) load (N); 3) sliding speed (m/sec); 4) sliding distance (m). Wear rate and coefficient of friction (COF) was the response characteristics studied. Subsequently, analysis of variance (ANOVA) was applied to evaluate the significance of each control factor on the response characteristics. Reinforcement and load were identified as the highly influencing significant parameters on the wear rate and COF using ANOVA analysis. Furthermore, a confirmation test was also performed to verify the experimental results. Analysis of SEM of the worn surface reveals that abrasive and oxidation were the dominant wear mechanisms during the tribo-test of Al 6061-graphene composites.

Synergy of wood ash on mechanical and sliding wear properties of banana/walnut-based epoxy composites and optimisation with grey relational analysis

This study investigates the sliding wear characteristics of wood ash-based banana/walnut reinforced epoxy composites using the hand layup technique. This research investigates the impact of wood ash on composites to obtain excellent wear resistance and moderate mechanical properties, which can be utilised in various engineering applications. As the percentage of wood ash increases in the composites, the tensile strength and hardness of the composites increase, but the impact energy declines marginally. The sliding wear test is carried out on a dry sliding wear test machine (pin-on-disc). The Grey-Taguchi method and optimal factor settings are used to evaluate the multiple responses of composites. The results showed that the most critical factor influencing the properties of composites is wood ash content (41%), accompanied by sliding velocity (35%), and lastly, the normal load (24%). Scanning electron microscopy was used to analyse the composites' worn surfaces to investigate the potential wear mechanism.

Erosion and wear analysis of fly ash filled GFRP composite

The present work involves the solid particle erosion behaviour and the dry sliding wear characteristics of glass fiber reinforced polymer (GFRP) matrix composite using fly ash as filler material is investigated. Five different composite samples (with 0, 5, 10, 15 and 20 wt.% of filler) are fabricated using the traditional hand lay-up method and characterized for their density and hardness properties. Subsequently, the erosion and wear behaviour of the presently prepared composite samples are investigated on air erosion tester and pin-on-disc tribometer, respectively. For the erosion test experiments are performed according to a full-factorial design of experiment (DOE) by considering the hardness of the composite and the impingement angle as the controllable parameters. For conducting the dry sliding wear test, the type of composite, load and speed are taken as input parameters and the experiment is carried out as per Box-Behnken DOE of Response Surface Methodology (RSM). The composite with 15 wt.% of filler depicted the highest hardness value. The wt.% of filler is found to have a significant effect on the erosion and wear behaviour with moderate filler (10 wt.%) providing the optimum result in both cases.

Tribological Behaviour of Aluminium 6061 Reinforced with Graphite and Chicken Bone Ash by using Stir Casting

Blending or supplementing metals with cutting-edge Metal Matrix Composites (MMCs) endeavours to improve the safety, reliability weight and productivity. A hybrid MMC was produced for the chamber liner of cutting-edge diesel motors. Dry sliding wear testing equipment, employing a pin-on-disc wear tester, is used to examine the wear properties of casted hybrid metal matrix composites. The examination shows that the wear opposition of Al-6061 is expanded while adding the chicken bone ash and graphite as support content. Within the current work, effort has been made to survey the tribological properties of aluminium as-projected combination test for Al amalgam and unadulterated aluminium. The operational boundaries were a typical load and sliding velocity of the pin concerning rotating disk at temperature. The medium utilized was dry and wet greasing. The amount of mileage has been decreased altogether in aluminium alloy similar to unadulterated aluminium. Dry condition testing showed huge loads of noise and a similarly more measure of mileage for both aluminium and aluminium alloy. The coefficient of contact for aluminium alloy in wet conditions was roughly steady up to the applied load and then diminished with additional utilization of load while the coefficient of friction for unadulterated aluminium was rising persistently with the load. Evaluation of the corrosion conduct of the aluminium MMC is achieved by the usage of the salt spray method or immersion test and the results are considered.

Influence of oxides on the formation of self-lubricating layer and anti-wear performance during sliding

Oxides are the key roles on the formation of self-lubricating layer (SLL) with anti-wear performance. In present study, dry sliding wear tests of 00Cr13Ni4Mo steel were performed to investigate the influence of oxides on SLL. The formation of SLL with different oxides was comparatively analyzed by the cross-sectional and surface morphologies. Mechanism of oxides on the integrity of SLL and anti-wear performance is discussed. It is confirmed that Cr-oxide, Fe3O4 and suitable SiO2 are the key to endow SLL with good self-lubricating performance while FeO, Fe2O3 and excessive SiO2 are opposite, good integrity of SLL is the prerequisite for anti-wear.

Evaluation of in-situ synthesised titania-zirconia-boron carbide composite cladding on Ti6Al4V substrate using continuous wave fibre laser

In this work, titanium metal matrix composite (TiC, TiB2, TiO2, ZrB2) cladding was synthesised by irradiating a fibre laser beam on a mixture of Ti6Al4V alloy, ZrO2, B4C powders pre-placed on Ti6Al4V alloy plate. The effect of varying wt.% of B4C on the microstructure, hardness, erosion, and wear properties of the composite cladding were investigated using XRD, XPS, EBSD, FESEM with EDAX, nano-indentation, and wear tests. Under the exposure of fibre laser on a mixture of preplaced powders, the in-situ formation of TiC, TiB2, TiO2, and ZrB2 ceramic particles have taken place and get uniformly dispersed in the molten titanium alloy matrix. The volume fraction of these phases increases with the increasing percentage of B4C. A black willow-shaped structure (TiB2) is observed in sample BM3 (30 wt% of B4C), along with grey cellular dendrites (TiC) dispersed uniformly in the matrix. The average microhardness of the claddings increases with the increase of B4C contents. The average weight loss of the cladding samples in dry sliding wear tests decreases with increasing the B4C content. The maximum microhardness of 1582.4HV300 is recorded in BM3 cladding, which is almost four times higher than the substrate material. The decrease in the average value of maximum nano-indentation depth with an increase in the content of B4C is in good agreement with the results of microhardness tests. The hardening of the cladding is also accompanied by increased values of parameters H/E (hardness(H)/Young's modulus (E)) and H3/E2(0.133), indicating better resistance to crack formation during indentation even at higher loads showing the cladding is hard as well as tough. The grain size variation and volume fraction of TiC–TiB2 obtained from electron backscatter diffraction test results agrees with cladding having these properties. The coefficient of friction (0.15–0.25) is found to be lower than the substrate material (∼0.3). The claddings also show good erosion resistance at ambient, 250 °C, 350 °C and 750 °C.

Development of novel Fe-based bulk metallic glasses with excellent wear and corrosion resistance by adjusting the Cr and Mo contents

In this work, a series of novel Fe80–x–yCrxMoyP10C7B3 (x = 0, y = 0; x = 0, y = 4; x = 5, y = 4; x = 15, y = 4; x = 20, y = 4; x = 15, y = 8 in at.%; denoted as CrxMoy) bulk metallic glasses (BMGs) with critical diameters in the range 1.0–2.5 mm were fabricated. The effect of Cr and Mo contents on the glass forming ability (GFA), thermal stability, mechanical properties, corrosion behavior, and wear performance of the these Fe-based BMGs were systematically investigated. A partial substitution of Fe by Cr and Mo was found to enhance the GFA of the Fe-based BMGs. The sample Cr15Mo4 exhibited the maximum critical diameter (2.5 mm), maximum temperature range of the supercooled liquid phase (55 K), and highest activation energy for the primary crystallization process (184 kJ·mol−1). Uniaxial compression and microhardness tests revealed that the compressive strength and Vickers microhardness of the Fe-based BMGs were in the range 3.0–3.7 GPa and 794–958 HV0.1, respectively, and increased with increasing Cr/Mo content. Electrochemical tests in a 3.5 wt.% NaCl solution showed that the Fe-based BMGs exhibited a significantly higher corrosion resistance than 316L stainless steel (316L SS) and 304L stainless steel (304L SS). The corrosion resistance of the Fe-based BMGs generally improved with increasing Cr/Mo content. The sample Cr15Mo4 exhibited the highest corrosion resistance with a self-corrosion and passivation current density ∼10−8 A·cm−2 and ∼10−6 A·cm−2, respectively. X-ray photoelectron spectroscopy of the samples revealed that compared to Cr15Mo4, there was a higher proportion of defective high-valence metal cation (Fe3+, Cr6+, and Mo6+) oxides and a lower proportion of stable low-valence metal cation (Fe2+, Cr3+, and Mo4+) oxides in the passive films of Cr20Mo4 and Cr15Mo8. This explains the reason why adding more than 15 at.% Cr and 4 at.% Mo degrades the corrosion resistance of the Fe-based BMGs. The dry sliding wear test demonstrated that the Fe-based BMGs exhibited significantly better wear performance than 316L SS and 304L SS. The wear rate and coefficient of friction of the Fe-based BMGs decreased with increasing Cr/Mo content. The sample Cr15Mo8 exhibited the lowest wear rate and coefficient of friction of 0.98 × 10−5 mm3·N−1·m−1 and 0.38, respectively. The Fe-based BMGs synthesized in this work, especially Fe61Cr15Mo4P10C7B3, exhibited a high GFA and excellent corrosion and wear resistance. Therefore, they have immense potential for various engineering applications.

Influence of Si3N4 on the Dry Sliding Wear Characteristics of Stir-Cast Cu-10Sn/xSi3N4 Metal Matrix Composite for Bearing Applications

Bronze metal matrix composites (MMCs) are futuristic materials that may find applications in automobile, aviation, and marine industries, specifically for propellers in submarines, bearings, and bushings for defence purposes. The present investigation studied the effect of Si3N4 (5, 10, 15 wt%) ceramic particles on the physical, metallurgical, and tribological behaviour of Cu-10Sn/Si3N4 MMCs. Cast rods of three composites and a base alloy were fabricated using the liquid metallurgy route. The microstructural characterisation for the cast samples was conducted using FESEM (Field Emission Scanning Electron Microscope), EDS (Energy Dispersive Spectroscopy), XRD (X-ray diffraction), and TEM (Transmission Electron Microscope), which revealed that the Cu-10Sn alloy reinforced with 5 wt% of Si3N4 had homogeneous distribution and perfect bonding of the Si3N4 with the bronze MMC. The dry sliding wear test was performed by varying parameters such as the applied load (10, 20, 30 N) and sliding velocity (1, 2, 3 m/s). The specific wear rate (SWR) increased against an increased load. However, the SWR and coefficient of friction decreased and then increased against an increasing sliding velocity due to tribolayer formation. The primary wear mechanism observed at low and high loads was severe delamination. In contrast, the wear mechanism was adhesion wear at high and low velocities. Amongst the researched samples, Cu-10Sn/5 wt% Si3N4 composites revealed the least SWR at a load of 10 N and sliding velocity of 2 m/s and hence can be recommended for manufacturing bearings and bushings in the automobile and defence industry.

Effect of spray angle and substrate material on formation mechanisms and properties of HVAF sprayed coatings

Thermally sprayed coatings are often used to enhance the surface properties (wear resistance, corrosion resistance, etc.) of engineering components in order to extend their performance and service lifetime. Typically, the industrial components to be coated possess complex geometries and are fabricated using different materials, which can influence the deposited coating's microstructure and performance. High-velocity air fuel (HVAF) process is a relatively new thermal spray processing technique that has shown tremendous potential to deposit high performance coatings for durable industrial components. However, no detailed studies have been reported on HVAF sprayed coating formation mechanisms so far in relation to the spray angle and substrate properties, and the influence of coating material on the above. The objective of this work was to study the influence of spray angles and substrate materials on splat characteristics, coating microstructure evolution, properties and performance for two distinct coating materials.In this study, one cermet (WC-CoCr) and one metallic (Inconel 625) feedstock were deposited onto three different substrates (aluminium alloy, carbon steel and Hastelloy-X) utilising different spray angles (40°, 60° and 90°). The coating evolution was analysed utilising SEM/EDS, image analysis, and micro-indentation. To determine the tribological performance, coatings were subjected to dry sliding wear test utilising alumina ball as counter surface and specific wear rates were obtained.The results showed that initial splat characteristics were substantially altered on changing the substrate and the spray angle. However, the final coating properties were not affected significantly even though the deposition rate was reduced significantly at lower spray angle, suggesting the versatility of the HVAF process.

Microstructure evolution and wear properties of ECAP-treated Al-Zn-Mg alloy: Effect of route, temperature and number of passes

In this study, the effect of severe plastic deformation on Al-Zn-Mg alloy was investigated by ECAP method. The ECAP process parameters were determined using Taguchi experimental design for different routes (A, B C and C), different temperatures (100, 150 and 200 °C) and different number of passes (2, 4 and 8). EBSD and TEM analysis were used for microstructural characterization of the samples and the dry sliding wear test was used to measure the mechanical strength. In the study of microstructural properties, it was determined that there was a direct relationship between the number of passes and temperature. With the increase in the number of passes and the decrease in the temperature, a severe decrease in grain size in the samples was observed. It was observed that the sample subjected to ECAP treatment with 8 passes at 100 °C in the B C route was microstructurally coaxial and had the smallest grain size, and the same sample showed the best wear properties.

Dry sliding wear investigation of graphene reinforced copper-silica sand composite by response surface methodology

In the present investigation, Cu-based metal matrix composites (MMCs) have been fabricated through powder metallurgy using silica sand micro-particles and graphene as nano-fillers, and their influence on wear behavior has been studied. The weight fraction of silica sand has been fixed to 5 wt. % and graphene nanoparticles have been varied from 0.1 to 0.3 wt. % in the steps of 0.1 wt. %. The investigated samples have been fabricated by cold pressing at 500 MPa, followed by sintering (750-900 °C × 2 h) in a nitrogen atmosphere. The wear behaviour of all fabricated samples has been done on a pin-on-disc wear tester at ambient conditions. Microstructural characterization such as Optical microscopy, X-ray diffraction (XRD), Energy dispersion spectroscopy (EDS), scanning electron microscopy (SEM), and Raman spectroscopy showed uniform dispersion of both silica and graphene nanoparticles. Relative density, hardness and wear resistance increased with the addition of graphene nanoparticles up to 0.2 wt. %. The electrical conductivity of the samples has been evaluated using four probes setup. Increasing the amount of graphene nanoparticles from 0.1 to 0.3 wt. % resulted in a decrease in the electrical conductivity of the sintered copper silica composite. The wear mechanism of worn surfaces has been analyzed and discussed using scanning electron microscopy. Adhesive wear, abrasive wear and delamination were the dominant wear mechanisms during the dry sliding wear test. Further, Response Surface Methodology (RSM) technique have been employed to investigate the influences of most dominating process parameters on responses like sintered density, hardness and wear loss. Finally, based on error analysis, model-predicted results and experimental data have been compared and found to be satisfactory. The percentage errors during the confirmatory test for sintered density, hardness and wear loss are 1.59, 2.06 and 2 respectively, which justify the worth of present research work.

Improvement of the Wear Resistance of Circular Saws Used in the First Transformation of Wood through the Utilization of Variable Engineered Micro-Geometry Performed on PVD-Coated WC-Co Tips

Reduced performance of circular saws due to premature chipping of their teeth has been a critical issue in woodcutting industry for many years. This research examined the impact of surface coating and variable engineered micro-geometry of the cutting edges of carbide teeth (tips) on the wear resistance of circular saws used in primary wood processing. CrN/CrCN/DLC, CrN/AlTiN, CrN/CrCN, and CrCN/TiSiCN were deposited on tungsten carbide-cobalt (WC-Co) substrates using the cathodic arc evaporation technique. The CrN/CrCN coating proved to be the one with highest wear resistance and adhesion among those studied. No sign of delamination was observed around the indentation of the CrN/CrCN coating after the adhesion test. Furthermore, no abrasion, delamination or crack was observed on the surface of the CrN/CrCN coating after the three-body abrasion wear test. The results of the dry-sliding wear test revealed that CrN/CrCN coating significantly decreased the wear rate of WC-Co substrates by 74%, 66% and 77% at sliding speeds of 50, 100 and 250 mm/s, respectively. Afterwards, a CrC/CrCN coating was deposited on the teeth of conventional circular saws. Next, the cutting edges of teeth were modified through variable engineered micro-geometry. Tests were conducted at a sawmill with three series of saws: 1-coated and edge-modified, 2-coated and conventional edge geometry, and 3-uncoated and edge-modified. Wood processing was performed during two shifts of 480 min each. The width of the wear land was the criterion used as the wear index. The results of industrial tests showed that saws with edge-modified teeth had significantly less chipping and no breakage at their corners compared to the saw without edge modification (conventional saw). After 480 min of sawing, the wear rate of the coated saw with edge modification decreased by 46% and 16%, compared to the coated saw without edge modification and the uncoated saw with edge-modified teeth, respectively. Those values reached 73 % and 41%, respectively, after 960 min of sawing. The study shows that by optimizing the surface chemistry and the geometry of the cutting edge of WC-Co tips, tool life can be significantly increased therefore reducing downtime due to saw replacement and resharpening, thus significantly increasing productivity in the first transformation of wood.

Influence of Alloying Element and Ageing on Microstructure and Dry Sliding Wear Behaviour of Cu-Zn-xNi Alloy

In this paper, we look at how different nickel concentrations (4, 8, and 12 percent) affect the microstructure, microhardness, and dry sliding wear behaviour of a Cu-Zn-xNi alloy. The alloy was created using a casting technique at 1100°C and a heat treatment method that included solution treatment at 600°C and ageing at 450°C for four hours each. Microstructure studies were performed on the developed alloys using a scanning electron microscope (SEM). To investigate alloy indentation resistance, an ASTM E384 microhardness test was performed. Tribological properties such as friction and wear were investigated using a pin on disc tribometer and a dry sliding wear test according to the ASTM G99 standard. SEM studies revealed α-phase (copper) and solid solution of zinc in cast alloys, while aged alloys revealed a similar structure but with the addition of Cu2NiZn precipitates. The microhardness values improved as the Ni content and ageing increased. The decrease in secondary dendrite arm spacing with increasing Ni content and ageing was attributed to the improvement. The coefficient of friction decreased as the load increased, but increased as the sliding velocity increased. However, as loads and sliding velocities increased, so did the wear rate. For the majority of loads and sliding velocities, the worn surface demonstrated abrasion as the dominant wear mechanism.