Wear Mass Research Articles

Fabrication of TC4/TiCp New Hip Prosthesis by Laser Cladding

Artificial hip prostheses are commonly utilized in total hip replacement surgeries. However, current single materials like metal, polyethylene, and ceramic do not satisfy the comprehensive performance requirements of prostheses, such as biocompatibility, wear resistance, and toughness. To address these limitations, a new metal–ceramic hip prosthesis which can be prepared by laser cladding technique is proposed. By combining the advantages of metal and ceramic, this prosthesis aims to overcome existing product limitations. A TiCp bioceramic coating is prepared on the TC4 surface, and its microstructure, mechanical properties, and biological characteristics are systematically analyzed. The results show that the TiCp phase is uniformly distributed in the coating. Additionally, dendritic TiCp at the bonding interface results in metallurgical bond between the coating and substrate. The α‐Ti phase in the matrix of the TiCp coating helps to enhance its fracture toughness and fatigue strength, while the solid solution of trace C elements in the matrix provides solid solution strengthening. Mechanical tests reveal that the microhardness of the TiCp coating is 2.5 times greater than that of the substrate, and the wear mass is reduced by 89.4%. Finally, the TiCp bioceramic coating is verified to be biocompatible, demonstrating excellent potential for use in hip prostheses.

A study on predicting the wear of TBM disc cutters using Cerchar testing

Estimating the disc cutter wear life or change time is a critical part of performance prediction for the application of hard rock TBMs. This paper examines the disc cutter wear rate and the number of required discs during the excavation of the Kanisib (or Zab) tunnel based on the transpositioning concept. The study covers the disc changes due to the normal wear process, leaving out those replaced due to mechanical/bearing failures. This study also analyzes TBM field performance and actual cutter consumption using a method, specific mass loss per volume (SMLV) excavated. SMLV considers the wear mass of a disc cutter relative to the disc cutters replacement for a given volume of excavated rock. Generally speaking, the disc SMLV incorporates critical parameters, and a formula is introduced to calculate it from the rock properties. The new model can be utilized for estimating disc life for any disc cutter size, diameter, and tip width. The predictive model developed in this study allows for estimating cutter life based on the location of disc cutters on the cutterhead. The proposed model uses rock mass parameter, namely the rock quality designation (RQD), and rock material parameters measured in a laboratory, including rock abrasion and strength. Rock abrasion is estimated by Cerchar abrasivity index (CAI) or modified Cerchar abrasivity index (MCAI). Furthermore, a new approach to Cerchar indices has been used, which is based on the pin mass loss instead of pin tip flat size, and as a result, new indices called CAIML and MCAIML are introduced. The correlation between predicted and observed values shows that the proposed model for specific mass loss per volume can predict the normal wear of disc cutters. Furthermore, the Cerchar indices calculated using the pin mass loss offered better correlations with field data than those specified based on the diameter of the pin tip flat. Overall, MCAIML exhibited the best correlation with the field observations compared to the other Cerchar indices.

Simulation experiment study on friction and wear of materials under high humidity conditions

Purpose The purpose of this paper is to examine the practicability of the self-designed ambient humidity controllable pin-disc/rolling multifunctional friction and wear test device and to evaluate the friction and wear characteristics of materials under diverse ambient humidity conditions in different contact forms. Design/methodology/approach The practicability of the self-designed multifunctional friction tester was examined by the friction and wear tests of materials under different ambient humidity conditions [65%RH, 98%RH (relative humidity)] in diverse contact forms (pin/disc and rolling). Meanwhile, the friction and wear properties of pin/disc samples also rolling samples were assessed from three aspects: average friction coefficient, wear mass and wear morphology. Findings The results prove that the self-designed multifunctional friction tester has practicability. Therefore, it can be used to simulate the friction and wear tests of materials under diverse ambient humidity conditions in different contact forms. Besides, it is evident that the wear damage of pin/disc and rolling samples are greatly improved under high ambient humidity conditions. And when other conditions are identical, the higher the ambient humidity, the smaller the average friction coefficient, wear mass and wear damage degree of pin/disc also rolling samples. Originality/value This paper offers a self-designed multifunctional friction and wear test device. And the tester not only can realize the control of test ambient humidity, but also achieve the wear test of pin/disc or rolling contact forms. The design and production of the tester can offer convenience for the research of tribology, and provide fundamental guidance for the study of materials under high humidity condition in diverse contact forms.

Impact of Cryogenic Treatment Process on the Performance of 51CrV4 Steel.

The working load on automotive components is continuously rising, and the mechanical performance requirements for component materials are rising along with the growth trend toward light weight and high dependability in automobiles. In this study, the response characteristics of 51CrV4 spring steel were taken to be its hardness, wear resistance, tensile strength, and impact toughness. Prior to tempering, cryogenic treatment was introduced. Through the Taguchi method and gray relational analysis, the ideal process parameters were discovered. The ideal process variables were the following: a cooling rate of 1 °C/min, a cryogenic temperature of -196 °C, a holding time of 24 h, and a cycle number of three. An analysis of variance revealed that the holding time had the greatest effect on the material properties, with an effect of 49.01%. The yield limit of 51CrV4 was increased by 14.95% and the tensile strength was increased by 15.39% with this group of processes, and the wear mass loss was reduced by 43.32%. The mechanical qualities had a thorough upgrade. Microscopic analysis revealed that cryogenic treatment resulted in refinement of the martensite structure and significant differences in orientation. Additionally, bainite precipitation occurred, exhibiting a fine needle-like distribution, which positively influenced impact toughness. Analysis of the impact fracture surface showed that cryogenic treatment led to an increase in dimple diameter and depth. Further analysis of the elements revealed that calcium (Ca) weakened the negative effect of sulfur (S) on 51CrV4 spring steel. The overall improvement in material properties provides guidance for practical production applications.

INCREASING THE HARDNESS AND WEAR RESISTANCE OF TECHNICAL TITANIUM BY ANODIC PLASMA ELECTROLYTIC CARBURIZING

The possibility of using the anodic electrolyte-plasma carburization technology in a non-toxic electrolyte to increase the microhardness and wear resistance of commercially pure titanium is considered. The morphostructure and roughness of the material surface after saturation were studied, the distribution of microhardness in the surface layer and the tribological behavior of the modified surface were studied. Wear resistance tests were carried out under dry friction conditions using tool alloy hardened steel as a counterbody. It has been established that electrolyte-plasma cementation in an aqueous electrolyte, containing ammonium chloride and glycerin, increases surface hardness by 3.5 times, up to 900 HV0.01, due to the formation of a diffusion layer. Tribological behavior is influenced by high-temperature oxidation of the surface, leading to the formation of an outer oxide layer, the formation of a modified layer and the titanium surface relief. The friction coefficient after treatment increases by 1.2 times, and mass wear decreases by 3.4 times compared to the untreated surface of titanium parts.

Modification mechanism of Ti-6Al-4V alloy with pre-coated Ti-Cu-Al multilayer film treated by ion nitriding: Experiments and first-principles calculations

In this paper, the Ti-6Al-4V(TC4) alloy specimens pre-coated with Ti-Cu-Al multilayer films were plasma nitrided at different temperatures (673K-823K), and their microstructure and mechanical properties were studied. Surface hardness changes induced by pre-coating combined with plasma nitriding were also analyzed and correlated with microstructural features and elemental distribution. Ti-Cu-Al multilayer films with clear interfaces on deformed TC4 alloy were fabricated. The multilayer structure survived after nitriding, and a thick gradient nitrided layer with a gradient distribution of N elements was formed. The bonded nitride on the surface provides high hardness, reaching 948HV at 723K. In addition, the nitride TC4 alloy's wear resistance exhibits a significant improvement compared with the untreated specimen, especially at 823K, the mass wear rate decreased by more than 80%. It is mainly attributed to the N/metal element gradient distribution of the thick nitride layer. The nitriding behavior of α-Ti/Cu/Al was investigated by first-principles calculations. According to the thermodynamic calculation results, N atoms preferentially occupy the octahedral interstitial sites of α-Ti and the tetrahedral interstitial sites of Al. It is worth noting that N atoms have poor thermodynamic stability in Cu, which is consistent with the experimental results. The calculated elastic properties agree with the experimental cross-sectional hardness results, showing a smooth decreasing trend of the complex modulus and hardness on the micrometer length scale and explaining the improved structure performance. These results may provide crucial inspirations for future experimental work preparing high-performance nitrided layers.

Talc modification with bis[3-(triethoxysilyl)propyl]tetrasulfide (TESPT)-based coating to improve the mechanical characteristics of silicone rubber

Rubber is a main material of prosthetic foot products. A local product of Indonesian prosthetic foot is available in the market. However, the quality of the product need to be improved. Several material formulations have been made to make prosthetic foot more elastic, strong, and affordable. An optimization formula of talc powder reinforced silicone rubber has been carried out in the previous study. However, the bonding between talc powder and silicone rubber is weak. In the present study, the talc powder is coated with a bis[3-(triethoxysilyl)propyl]tetrasulfide (TESPT) in order to obtain strong bond between talc powder and silicone rubber. Mechanical characterizations were conducted to compare the composites with and without TESPT coating. The characterization include tensile and hardness tests. The tribometer tests are also conducted to compare both composites, it evaluates the value of friction and wear mass of the composites. The results show that the composites using coated talc powder can reduce wear and friction force. The friction and wear of composites containing coated talc powder is better than the local products. The hardness of the composites containing coated talc powder increases compared to those without coating. While the use of coated talc powder reduces the tensile strength and elongation at break.

Preparation and properties of graphene composite lubricants additive used for cylinder liner in marine diesel burning low sulfur fuel oil

In recent years, abnormal wear issues have emerged in cylinder liner-piston rings (CL-PRs) in marine diesels that burn low-sulfur fuel oils (LSFO). To address this issue, a graphene-attapulgite composite additive was prepared and characterized as detailed in this report. Then, the tribological properties and corrosion resistance of this graphene-attapulgite were investigated when it was used at various concentrations as a multifunctional composite lubricant additive in simulated LSFO lubrication conditions. It was found that the appropriate concentration of the additive in a lubricant produced excellent anti-friction and anti-wear properties. This was when the additive was at 0.25 wt% concentration in normal lubricating conditions, where the friction coefficient and wear mass loss were reduced by 22.7% and 44.1%, respectively. Additionally, the impermeability of the graphene additive was found to improve the corrosion resistance of the lubricant. These findings revealed the mechanism of the graphene-attapulgite additive for friction reduction and corrosion resistance of cylinder liner in simulated LSFO lubrication conditions, which provided an inhibition method to prevent abnormal wear of cylinder liner in marine diesel burning LSFO.

CFD-DEM coupled calculation of wall wear characteristics during particles flow impacting the wall process

The continuous impact of the particles flow on the wall during industrial bulk material transport can lead to wall wear. In this paper, a physical model of the particle flow impacting the wall at different angles is established, and the wear condition of the particles flow impacting on the wall is studied by using the coupling method of CFD-DEM. Firstly, the accuracy of the erosion model is verified by the existing experimental data. Secondly, the effects of particle incidence angle, particle velocity and particle volume fraction on wall wear are analyzed by numerical calculation. The results show that the mass loss and erosion ratio of the target plate are the largest when the particle incidence angle is between 15° and 30°. When the particle incidence angle is near 45°, the maximum wear depth will appear on the wall surface. The increase of particle impact velocity led to an exponential increase in the mass loss, erosion ratio and wear depth of the target plate, but did not change the wall wear morphology. The particle volume fraction is positively correlated with the mass loss of the target plate. With the increase of particle volume fraction, the change of erosion ratio is more obvious at 90° impact, but has little effect at 45° impact. The change of particle volume fraction has an important effect on the wall wear morphology.

A novel finding on tribological, emission, and vibration performances of diesel engines linking to graphene-attapulgite lubricants additives under hot engine tests

The cylinder liner-piston ring (CL-PR) that worked under harsh conditions is extremely susceptible to wear, and its friction loss is the primary source of mechanical loss of engines, affecting its equipment reliability and energy consumption. Recently, the use of low sulfur fuel oils (LSFO) aggravated the wear of the CL-PR, further increasing friction loss. Furthermore, the emissions of diesel engines also affect the environment and human health. In this study, the graphene-attapulgite (G-ATP) additive was prepared and applied to engines in response to these challenges. The prepared G-ATP additive was dispersed into 5040 lubricating oil with a 0.25 wt% concentration, then the effects of the additive on engines were investigated under hot test conditions with a speed of 1750 rpm. It was found that the G-ATP additive displayed excellent tribological properties, the wear mass loss of the piston ring was reduced by 64.5% with the addition of the G-ATP additive, and the wear of the cylinder liner was significantly reduced. Meanwhile, owing to the excellent tribological properties and thermal conductivity of the G-ATP additive, the HC and NOx emissions of the engine were reduced by 3.0% and 6.1%, respectively. Additionally, the vibration performances of the engine were improved by 42.1% in the final stage. These findings revealed the potential mechanism of the G-ATP additive for performance enhancements of diesel engines, as well as the relationships between the emission and vibration of engines and tribological properties of CL-PRs, which promote the energy saving and emission reduction of engines.

Effects of ultrasound on the CrMnFeCoNi coatings with different TiC contents fabricated by laser cladding

The present study systematically explores the effect of ultrasound on the CrMnFeCoNi + x(TiC) coatings fabricated by laser cladding. The investigations revealed that the microstructure of the CrMnFeCoNi + x(TiC) cladding layers prepared without ultrasonic assistance is mainly columnar dendrites. With the introduction of ultrasound, the columnar dendrites break up and form equiaxed dendrites. The aggregation of TiC is reduced in the 2 wt% TiC cladding layer prepared by ultrasonic assistance relative to that without ultrasonic assistance. On the other hand, increasing the TiC to 4 wt% in the cladding layer resulted in the spreading of TiC in a wider range along the grain boundary upon ultrasonic treatment. Furthermore, the grain size shows no obvious changes and there is no significant textural characteristics in cladding layers prepared with and without ultrasonic assistance. In contrast, the effect of ultrasound on the TiC distribution is minimal in the cladding layer with 10 wt% TiC. Besides, the introduction of ultrasound could effectively reduce the mass wear rate and the friction coefficient of the CrMnFeCoNi cladding layer with different TiC content except that of 10 wt% TiC cladding layer. The large size and small number of TiC particles in ultrasonic-assisted and non-ultrasonic-assisted 10 wt% TiC cladding layers leads to a decrease in the number of forming corrosion galvanic cell and a decrease in the influence on the dislocation density. Therefore, both ultrasonic-assisted and non-ultrasonic-assisted 10 wt% TiC cladding layers exhibite high electrochemical corrosion resistance. The effect of ultrasonic vibration on CrMnFeCoNi cladding layers with different TiC contents can be explained by the influence of TiC on ultrasonic attenuation.

Investigating the Effects of Graphene Nanoplatelets and Al4C3 on the Tribological Performance of Aluminum-Based Nanocomposites

The study investigates the effects of graphene nanoplatelets (GNPs) on the tribological properties of aluminum-based nanocomposites, both annealed after extrusion and non-annealed. It also examines the role of nanosized Al4C3 (aluminum carbide), which forms in the annealed Al/GNPs nanocomposite, on the tribological performance of the nanocomposites. The nanocomposites were fabricated using the powder metallurgy method. The microstructure of the composite materials was characterized using SEM, EDS, XRD and TEM techniques. The coefficient of friction (CF) and mass wear of the composites were measured using a pin-on-disk test under dry sliding friction conditions. The results showed that adding GNPs increased the coefficient of friction (CF) of the nanocomposites by up to 44% at 0.1 wt.% GNP, but the CF decreased by 15% at 1.1 wt.% GNP. The optimal concentration of GNPs for minimizing the CF and mass wear of Al-based nanocomposites was 0.1 wt.%. Additionally, the presence of Al4C3 in the annealed Al/GNP nanocomposite had a positive effect on the CF at low GNP concentrations, with a 38% increases at 0.1 wt.% GNP, but this effect diminished as the GNP concentration increased. The study also found that the mass wear of the nanocomposites increased with the GNP concentration, with a 46% increase in the mass wear from 0.1 wt.% GNP to 0.5 wt.% GNP and a 202% increase from 0.1 wt.% GNP to 1.1 wt.% GNP. The presence of Al4C3 also affected the mass wear, with the effect diminishing as the GNP concentration increased. The study observed an increase in the mass wear with the increase in the GNP concentrations, but the mass wear of the annealed Al/GNPs with 1.1 wt.% GNP and Al4C3 was 52% lower than the Al composite with 1.1 wt.%. Overall, this study provides insights into the role of GNPs and Al4C3 on the tribological performance of aluminum-based nanocomposites.

Microstructure and Wear Resistance of Ti5Si3/Ti3Al Composite Coatings Prepared by Laser Cladding on TA2 Titanium Alloy

In order to improve the wear resistance of titanium alloy, a Ti5Si3/Ti3Al composite coating with improved wear resistance was successfully prepared by laser cladding TA2 titanium alloy using the double-layer presetting method of Ti-63 wt.% Al mixed powder layer/Si powder layer. The microstructure, phase composition and wear resistance of the coating were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM) and pine-disk friction and wear method. The results show that the coating is mainly composed of the Ti5Si3 primary phase and Ti5Si3/Ti3Al eutectic structure. The microhardness of the coating is higher than that of the matrix. The average microhardness of the coating is about 668 HV0.1, which is 3.34 times that of the matrix. The coating significantly improves the wear resistance of the TA2 matrix, and the mass wear rate is 1/5.79 of that of the TA2 matrix. The main wear mechanisms of the coating are abrasive wear, adhesive wear and oxidative wear, whereas the main wear mechanisms of the TA2 matrix are adhesive wear and oxidative wear.

Effect of diamond like carbon coatings on reducing sliding fit joint interfacial wear damage on Al5083 alloy

Wear is an important concept and is being given importance in different manufacturing industries. In every mobile joint, studies in interaction between sliding surfaces are very important. This is due to the wear that occurs in between the sliding surfaces. A lot of sliding fit joints are fabricated and used in production companies and transportation industries. In this manuscript, an attempt has been made to reduce sliding wear of Al 5083 alloy materials by coating it with diamond like carbon material. Using high velocity oxy fuel thermal spray coating, diamond like carbon materials were coated over Al 5083. Then it was subjected to wear testing by using pin on disc wear testing equipment. Wear tests were conducted by using petroleum lubricant and also in dry conditions. A considerable improvement in wear resistance was observed on using diamond like carbon coatings. Using scanning electron microscopy, the alloy Al 5083 material was evaluated for microstructural variations on conducting wear studies, before and after coating it with diamond like carbon material, with and without lubrication. The variations in coefficient of friction, specific wear rate and wear mass loss were studied under lubrication and without lubrication, with and without diamond like carbon coating. Microstructural evaluation of wear tested surfaces exhibited micro wear, micro voids, coating pull outs, abrasive wear and micro cracks.

Identification of Impact Frequency for Down-the-Hole Drills Using Motor Current Signature Analysis

In rotary-percussion drilling, the impact frequency is a crucial variable that is closely linked to operational factors that determine the efficacy of the drilling process, such as the rate of penetration, bit wear, and rock mass characteristics. Typical identification methods rely on complex simulation models or the analysis of different sensor signals installed on specially adapted setups, which are difficult to be implemented in the field. This paper presents a novel study where the impact frequency is identified by motor current signature analysis (MCSA) applied to an induction motor driving a DTH drilling setup. The analysis of the case study begins with the definition of characteristic drilling stages where the pressure and sound signals allow the detection of an impact frequency of 14.10 Hz, which is then used as a reference to validate three MCSA identification approaches. As a result of the analysis, the envelope approach is the most robust for nearly real-time implementations considering its simplicity and range of coverage. Experimental results provide evidence about the feasibility of the proposed MCSA methods to be integrated into Measurement-While-Drilling (MWD) systems to improve drilling condition monitoring and rock mass characterization.

The Impact of Laser Beam Power on the Microstructure and Some Mechanical Properties of Laser-Alloyed Inconel®600 with WC Particles

Laser surface alloying with WC particles was used in order to improve the wear resistance of Inconel®600-alloy. The applied processing parameters ensured appropriate conditions for the production of composite layers enriched with WC particles that did not melt during the process. As a consequence, the produced layers contained globular shaped WC particles that were well bonded in the matrix. The WC particles were characterized by high hardness HIT = 31.25 GPa and a high Young's modulus EIT = 609.33 GPa determined by nanoindentation. The most important parameter influencing the thickness of the layer, the percentage of WC particles in the layer and the wear resistance of the produced layers was the power of the laser beam. Three values of laser beam power were used: 1.3 kW, 1.56 kW, and 1.82 kW. An increase in the laser beam power resulted in an increased thickness of the layer from 435 µm to 685 µm. Simultaneously, when the power of the laser beam was higher, the depth of re-melting of the substrate material increased. This was the reason for a decrease in the percentage of WC particles in the composite layer. The layer produced by laser beam power of 1.3 kW contained 20.59% of WC particles, whereas the highest power of the laser beam (1.82 kW) ensured a percentage of WC particles of about 9.46%. As a result, the increase in the laser beam power was the reason for the reduction in the wear resistance of the composite layer. The lowest mass wear intensity factor (Imw = 6.4 mg·cm-2·h-1) characterized the layer produced at laser beam power of 1.3 kW, and the highest Imw (18.5 mg·cm-2·h-1) was obtained for the layer produced with a laser beam power of 1.82 kW. However, all the produced composite layers contained WC particles, which ensured improved wear resistance when compared to the Inconel®600-alloy without the layer (Imw = 60.9 mg·cm-2·h-1).

Effect and optimization of tribological parameters upon wear responses of TiAlN coating

This study investigated the relative effects of tribological process parameters and their optimization for wear responses of a TiAlN thin film deposited on heat-treated and plasma-nitrided novel MDC-K hot work tool steel. The effects of tribological process parameters were studied by conducting a tribological test on the TiAlN thin film against a tungsten carbide (WC) counterbody. The researchers considered three tribological process parameters – namely, sliding velocity, applied load and sliding distance – to conduct the tribological test and study the effect of the parameters on five different wear responses – namely, friction coefficient, surface roughness (R a), wear depth, wear mass loss and hardness. The relative effects of the process parameters were studied using contour plots, and the individual effects and contributions were analyzed using an analysis of variance test. Further, the overall evaluation criteria method was employed to select the optimal settings of tribological process parameters based on the experimental results. Finally, the surface morphology of the worn TiAlN surface against the best and worst parametric settings was evaluated using scanning electron microscopy integrated with energy-dispersive X-ray spectroscopy to investigate the underlying wear mechanisms.

ВЛИЯНИЕ СТРУКТУРЫ ЖЕЛЕЗО-ТИТАНОВЫХ ГАЗОТЕРМИЧЕСКИХ ПОКРЫТИЙ НА ИХ ИЗНОСОСТОЙКОСТЬ

The paper studies the structure, phase composition and properties of thermal sprayed coatings made of Ti4Al titanium alloy and “Ti4Al + AISI420” pseudoalloy obtained by hypersonic metallization. It is shown that the deposited coatings include in the phase composition a large amount of titanium nitride TiN (up to 70 vol.%), which is formed during the metallization process. At the same time, an increase in propane pressure during metallization from 0.3 to 0.4 MPa leads to a slight decrease in the titanium nitride content in the sprayed coating. It is associated with an increase in the flight velocity of molten titanium droplets in an atmosphere of ionized gases and, accordingly, a decrease in the time of their interaction with ionized air nitrogen atoms. The porosity of the sprayed coatings made of titanium alloy Ti4Al is 30–35 vol.%, and their hardness and microhardness are 500–650 HV 1 and 1,300–1,600 HV 0.1, respectively. Coatings made of “Ti4Al + AISI420” pseudoalloy have a reduced porosity of 10–15 vol.%, and their hardness and microhardness are 500–600 HV 1 and 900–1,300 HV 0.1, respectively. It is shown that coatings made of Ti4Al alloy and “Ti4Al + AISI420” pseudoalloy are characterized by increased wear resistance under friction without lubricant. In particular, the intensity of mass wear of coatings Iq made of Ti4Al titanium alloy, obtained at propane pressures of 0.3 and 0.4 MPa, is 2.5–2.6×10–3 mg/m, and Iq for coatings made of “Ti4Al + AISI420” pseudoalloy is 1.0–1.1×10–3 mg/m. The reduced values of mass wear intensities of coatings made of “Ti4Al + AISI420” pseudoalloy are associated with the presence of TiN in them and relatively low porosity.

Исследование антифрикционных и противоизносных свойств смазочных материалов судового назначения, содержащих слоистый модификатор трения

The paper highlights the results of anti-friction and anti-wear tests of samples of lubricating media containing a layered friction modifier - molybdenum diselenide. The main variable test conditions are the load on the test samples, volume concentration of the layered friction modifier in the lubricating oil, preliminary storage time of the lubricating composition before testing. The main evaluation criteria are the mass wear of samples, wear intensity, friction coefficient. Each of the eight test cycles was implemented on a tribotechnical installation of an original design using a cylindrical contact type. The resource indicators transferred from the model conditions of the tests to the real tribological unit “ring-cylinder” of a marine diesel engine 6ChSP 18/22 were evaluated. According to the results of tribological studies, the effect of increasing the load on the model friction unit of the installation, containing a cylindrical wear pair of alloyed gray cast iron, was revealed, as a result of which the mass wear of the annular movable sample increases, and the resource transferred to the real tribological interface of the marine diesel engine “ring-cylinder” decreases in 1.13-1.23 times. The greatest influence on the wear indicators of model samples and the resource transferred to the real “ring-cylinder” interface of a marine diesel engine is the time of preliminary storage of a lubricant composition containing molybdenum diselenide as an additive. It has been proven that the deterioration of anti-friction properties (an increase in the average surface temperature of a segment sample and the friction force) is largely affected by a decrease in the volume concentration of an anti-wear additive in the oil. It has been found out that serious changes in the indicated estimated parameters are valid for the smallest loading step on the samples. General recommendations are formulated for the use of antiwear additives considered in the studies. It has been proved that storing lubricating compositions with additives is possible for a period of no longer than 3-4 days at given volume concentrations in the range of 0.5-1.0%, since if this period is exceeded by 25-40%, the diesel CPG resource may be halved with increased wear of its piston rings and cylinder liners.

Influence of shielding gas on machining and wear aspects of AISI 310–AISI 2205 dissimilar stainless steel joints

Abstract In this article, the effect of shielding gas combinations on gas tungsten arc-welded dissimilar AISI 310 steel and AISI 2205 steel joints was investigated. Two gases such as nitrogen and carbon dioxide were substituted in argon shielding gas and its corresponding improvement in the mechanical, microstructural, machining, and wear aspects of the dissimilar AISI 310–AISI 2205 joints was studied. Weld bead studies, tensile, and weld region microhardness were conducted. X-ray diffraction studies revealed joint intermetallics, and microstructural evaluation was conducted. Machining studies were conducted using drilling experiments. Using local analysis and global analysis, the cutting force variations in the feed direction and cutting direction were studied. Wear tests revealed that the variations in traction force, specific wear rate, coefficient of friction and tribo wear mass loss were studied. A considerable improvement in wear characteristics of AISI 310–AISI 2205 joints was observed by substituting CO2 and N in shielding gas.