EFFECT OF HUMIDITY ON TRIBOLOGICAL PROPERTIES OF SELECTED FRICTION JUNCTIONS WITH AN EVALUATION OF ACOUSTIC EMISSION

The study aimed to compare the effect of humidity on the operation of tribological systems. The tested friction and wear are external properties; therefore, their values may differ significantly depending on the operating parameters of the friction junction and environmental conditions. Tribological tests were carried out on a TRB3 tribometer in a dry sliding mode at a relative humidity of 50% ± 5% and 90% ± 5% in the ball-on-disc configuration with a load of 15 N. The friction junction consisted of a sample made of 100Cr6 steel, and three counter-samples were made of 100Cr6, SiC, and Al2O3 steel. The geometric structure of the surface was examined with an optical profiler. The tribological test results showed reduced linear wear and friction coefficient at a relative humidity of 90% ± 5% compare to its 50% ± 5%. The paper also presents the results for the sound recorded in the 16-bit linear PCM standard and analysed in a Spectra-Plus program.

Wear and Friction properties of H-Al-17Si alloy with dry, lubrication and coated (DLC-Star) conditions under HFRR

Dry, lubrication (SAE15W40), and coated (DLC-Star) reciprocating tribological tests on rapid solidified AlSi17Cu3.5-4Mg0.6-0.8 alloy was conducted using a high frequency linear reciprocating rig (HFRR) at ambient temperature. The alloy fabricated with the rheo-stir squeeze casting procedure under T-6 condition. However, at different loading (0-30 N) conditions, wear and friction properties of rapid solidified H-Al-17Si alloy are investigated. It is observed that the lower friction coefficient value obtained for DLC-Star coated H-Al-17Si alloy compared to dry and lubrication conditions. Though, for dry and lubricated sliding, the obtained wear coefficient values are 2.9X10-3 mm3/N.m and 4.0X10-4 mm3/N.m. A lower coefficient of wear value of 5.4X10-5 mm3/N.m was recorded with DLC-star coating under dry conditions. The alloy wear coefficient values first increases with applied load (up to 20 N) and then decreases (20 N to 30 N). EDS, AFM surface roughness profilometer, SEM, and advanced metallurgical microscope (AMM) analysis techniques used for the characterization of surface morphologies. The developments in friction and wear coefficients were fundamentally ascribed to the dispersion and size of primary Si elements and the development of tribo-oxide films on the rapid solidified AlSi17 alloy coated (DLC-Star) surfaces.

Experimental investigation on the friction characteristics of hazelnut powder reinforced brake pad

After the realization that asbestos fiber is harmful to human health, efforts to produce organic and environmentally friendly brake pads have increased. In this study, an environmentally friendly brake pad (NUS sample) was produced with the addition of 3.5% hazelnut shell powder. Hardness and density measurements of the brake pad sample were made. Chase type device was used for the wear and friction tests. The experiments were done according to the SAE J661 standard. The average friction coefficient value obtained as a result of the experiments was found to be 0.435 µ. Bu değer standartlara uygundur ve “FF” sınıfı aralığındadır. This value complies with the standards and is in the "FF" class range.

Effects of Particle Size and Composite Composition of Durian Peels and Banana Midribs' as Reinforcement Components on Resin-Based Brake Pad Performance

This study aims to determine the effect of particle size and material composition on the performance of resin-based brake pads. Experiments were carried out by mixing 75% UPR with durian peel and banana midribs fibers using ratios of 1/1, 3/2, and 2/3 at particle sizes of 104 and 250 μm. The experimental results shows that decreasing the particle size improves the mechanical properties of brake pads, but gives a high wear value and a low coefficient of friction. In addition, an increase in the percentage of banana midrib fibers as a whole provides better brake pad performance. The results of the comparison between commercial-based brake pads confirm that agricultural waste is potential as an alternative to friction materials in brake pads. Brake pad with a fiber ratio of 2/3 104 μm had highest values of hardness, wear and friction coefficient, namely 20.33 N/cm3, 2.02 x 10-4 g/s.mm2, and 0.2465. while the 1/1 250 μm and 3/2 250 μm had the lowest coefficient values and compressive strength of 0.1195 and 9.14 N/cm3. This study demonstrates the use of biomass waste as an alternative to friction material to overcome the dangerous problem of using asbestos in brake pads.

Influence of Sandblasting Process on Tribological Properties of Titanium Grade 4 in Artificial Saliva for Dentistry Applications

Titanium Grade 4 (Ti G4) is widely used in medicine for dental implants. The failure-free life of implants depends on their properties such as resistance to wear and friction processes. This paper presents an analysis of the influence of sandblasting on tribological wear of commercial dental implants made of TiG4 in artificial saliva. Tribological wear measurements were performed in a reciprocating motion in the ball-on-disc system. The scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS) method was used to characterize the surface of the implants before and after the tribological wear test. The microhardness of Ti G4 was measured before and after sandblasting by the Vickers method. The contact angle was determined by the method of sitting drop in air. The residual stress test using the X-Ray Diffraction (XRD) single-{hkl} sin2ψ method was carried out. The compressive residual stress of 324(7) MPa and surface hardening of Ti G4 was revealed after sandblasting with Al2O3 particles of 53–75 μm in diameter. It was found that sandblasting changes the surface wettability of Ti G4. The intermediate wettability of the mechanically polished surface and the hydrophobicity of the sandblasted surface was revealed. Sandblasting reduces the tribological wear and friction coefficient of Ti G4 surface in saliva. The three-body abrasion wear mechanism was proposed to explain the tribological wear of Ti G4 in saliva.

Wear and Residual Stress Analysis of Waste Sea Shell and B4C Particles Reinforced Green Hybrid Aluminium Metal Composite

Present work, evaluates the effects of Sea shell and B4C powder on the mechanical behavior of the aluminium material (Al 6082). Stir casting method was used to fabricate a hybrid composite of Al 6082 with sea shell and B4C. A linear reciprocating tribometer was used to evaluate the wear and friction behavior. The addition of sea shell and B4C particles, resulted in 7-13 % reduction in coefficient of friction and 32-43 % improvement in wear resistance as compared to the Al 6082 alloy. The average Vicker hardness was also improved by 20-70 %. The residual stresses developed during the mechanical testing were also measured to inspect the generation of residual stresses in the fabricated composite. Optical micrographs and scanning electron microscope (SEM) were obtained to analyze the prepared composites for the wear behavior. Waste sea shells were reinforced with B4C in Al 6082 alloys. Microhardness along with microstructure and residual stress of the developed green hybrid aluminium metal composite are compared and presented. The wear and friction data have also been shown in this paper for the use of green hybrid aluminium composite in tribological applications.