Papers by Keyword: Tribological Properties

Abstract: In this paper, the influence of laser surface alloying on the structure and mechanical properties of aluminium alloy was analysed. As a parent material aluminium EN AC-51300 alloy was applied. The laser surface alloying was executed by direct introduction of metallic powder Fe/Cu into the remelted area (molten pool). As a heat flux, the Hight Power Fiber Laser (HPFL) has been used. Metallic powder before the treatment was mixed in a ball mill and dried on the hot plate (90°C temperature). The mechanical and tribological properties of alloyed surface were analysed including hardness (HRF), microhardness (HV_0.1) and ball-on-plate wear test. The structure of the laser alloyed surface was evaluated by light and scanning electron microscopy.

Abstract: Tungsten Carbide (WC) hard coating is widely used to coat the surface of the steel tools which provide tribological properties. In this paper, 0.25 wt% & 0.35 wt% of Carbon Nanotubes (CNT) were mixed with tungsten carbide (WC) powders as the feedstock powders. Method of solution dispersion in ethanol media using an ultrasonic device was used for coating the surface of WC powders with CNT powder. The mixed powders were then used as the feedstock powder to coat onto the surface of tool steel using the flame spraying process. The coated surface microstructures were observed under a scanning electron microscope (SEM), x-ray diffraction (XRD), and the energy dispersive spectroscopy (EDS) was used for the phase characterization and identification. The wear rate of coated steels was determined using the Ogoshi machine, and the Vickers hardness method used to measure their microhardness. The effects of CNT on the microstructure of the coated material and the surface mechanical properties were investigated. The results showed that the mixture powder preparation using an ultrasonic method in SDS solution and the ball-milling process was suitable to disperse the CNT on the surface of WC feed powders due to produce an adequate relationship between CNT' and WC powders increasing the surface mechanical properties of coatings. The wear resistance of the coated material produce using the mixture of WC powder with 0.35 wt% CNT increased around 50% higher than the WC coated steel without CNT addition. Also, the hardness of coating reinforced CNT increased significantly compared with the hardness of WC coated and the steel substrates. Microhardness value from the base metal to the WC-CNT coated steel increased from 550 HV to 1717 HV and also the wear rate from the base metal to the WC-CNT coated steel decreased from 0.86 mm³/min to 0.017 mm³/min. These results indicate that CNT is an excellent alternative to improve the surface mechanical properties of WC coatings.

Abstract: In the current work, wear behavior of plasma processed LM6 alloy is investigated. LM6 alloy was prepared by plasma technique. The samples were aged at 350^°C & 450^°C for 2 hours followed by water quenching. A comparative study of the metallographic structure and properties viz. hardness, density and wear of the non-heat and heat treated alloy samples were carried out. A very fine lamellar structure is observed in case of 450^°C heat treated samples than that of sample heat treated at 350^°C and non-heat treated samples. Highest hardness value of 68.11 VHN is observed with the sample heat treated at 450^°C. Density is found to be the lowest in non-heat treated samples and it increases with increasing heat treatment temperature. Wear experiments were carried on a pin-on-disc set up (of Ducom make), varying applied loads (between 10-40Newton and varying sliding speed (from 0.94 m. s^-1 to 2. 83m.s^-1). Maximum wear resistance is observed with the specimen heat treated at 450^°C.

Abstract: Carbon fiber epoxy resin composite and polyimide material are likely to be applied to pulley-guideway system of the new satellite antenna. Their tribological properties have effects on the motion characteristics of the pulley-guideway system. To master the tribological properties of carbon fiber epoxy resin composite and polyimide material, this paper carries out tests of tribological properties and wear behavior of carbon fiber epoxy resin composite and polyimide material at 130°C and 30°C. Carbon fiber epoxy resin composite is used as the grinding specimen and polyimide material is used as the counter-grinding specimen. Tribological properties of this material pairs is studied under diverse linear velocity and external loads. The results show that friction coefficient of this material pairs is stable under different conditions, especially at 30°C. Meanwhile, wear behavior of this material pairs is mainly affected by ploughing of surface roughness at low temperature, while by surface micro-spalling at high temperature.

Abstract: In this paper, an investigation of tribological properties of 3D printed samples with various filling is performed. The samples are made of biodegradable and non-toxic polylactic acid (PLA) that could be used for medical purposes as well as for rapid prototyping. The sample's properties, such as friction coefficient and temperature in contact area are defined by using the universal friction machine.

Abstract: The goal of this research work is to study the role of equal channel angular pressing on consolidation behavior of machined chips of CP Al through ECAP. The chips are collected by orthogonal cutting with cutting edge angle 75° and depth of cut 0.2 mm. The ECAP die with Φ = 90° (channel angle) and Ψ = 20° (corner angle) is used for consolidation of machined chips. The consolidation is done by pre-heating the chips at 200°C upto four passes through processing route B_C. The maximum density of 99% and hardness of 94 HV was obtained after 4 ECAP passes. Tribological properties is evaluated by Pin-on-disc dry wear testing for three different loads at a constant sliding speed 750 RPM and distance of 5 kms. Chip consolidated CP Al is inferior in wear resistance with as-received CP Al owed to localised debonding of chips with the sliding disc.

Abstract: Lignite bottom ash is an industrial byproduct from the combustion of lignite coal in electric power plants. The ash is composed of various hard metal oxides, and therefore may be suitable for use as a low cost friction modifier in friction materials. This research studied the effect of lignite bottom ash additions (up to 20 weight percent) on the tribological properties of a graphite-steel composite (5 weight percent graphite and 95 weight percent high carbon steel). The powder compositions were uniaxially pressed with 300 MPa applied pressure to produce disc shaped samples. The samples were sintered at 1,100 °C for 30 minutes in a reducing atmosphere of 90 percent nitrogen and 10 percent hydrogen. The friction coefficients were measured using a ball-on-disc tribometer. It was found that the addition of bottom ash increased the friction coefficients of the samples due to the increased abrasiveness provided by the bottom ash. The density of the samples was reduced due to the lower theoretical density of the bottom ash compared to the steel that it replaced. The hardness of the samples were found to be independent of the amount of lignite bottom ash, possibly as a result of a hard particle reinforcement effect.

Abstract: This study examined the effect of waste-derived calcium sulfate additions (2 to 8 weight percent) on the tribological properties of a sintered high-carbon steel material, commonly used for frictional applications. The calcium sulfate powder was obtained by crushing and subsequent calcination of waste plaster molds previously used for slip casting of ceramics. Samples were made using the powder metallurgy method. Powder mixtures were uniaxially die compacted and sintered at 1,100°C for 30 minutes in a reducing atmosphere. It was found that the density of the samples decreased with increased amounts of calcium sulfate. This was due to the lower theoretical density of the calcium sulfate as well as volumetric expansion of the samples. Ball-on-disc tribological testing was performed at room temperature. The addition of calcium sulfate resulted in an increase of the kinetic friction coefficient. The measured wear volume was slightly reduced with the addition of calcium sulfate less than 6 weight percent, beyond which the wear increased. The hardness of the samples was reduced with the addition of calcium sulfate. Increased calcium sulfate content decreased the sample deformation resistance while increasing the kinetic friction coefficient and the wear. This was likely due to the microstructural changes of the samples, which will be discussed.

Abstract: The peculiar feature of friction materials to absorb the kinetic energy of rotating wheels of an automobile to control the speed makes them remarkable in automobile field. The regulation of speed cannot be achieved with the use of single phase material as a friction material. Consequently, the friction material should be comprised of composite materials which consist of several ingredients. Incidentally, the friction materials were formulated with friction modifier, binders, fillers and reinforcements. Due to its pleasant physical properties, asbestos was being used as a filler. Past few decades, it is found that asbestos causes dangerous cancer to its inhaler, which provides a scope its replacement. Several attempts have been made to find an alternative to the hazardous asbestos. The efforts made by different researchers for the impact of every composition of composite friction material in the field are reviewed and studied for their effect on the properties of friction material. Surface morphological studies of different friction material are compared to interpret the concept of surface wear and its correlation with material properties.

Abstract: A series of ZrN-Ag nano-composite films were deposited using the RF magnetron sputtering system. The microstructure, mechanical properties and tribological performances were investigated. The results showed that ZrN-Ag films were composed of face-centered cubic (fcc)-ZrN and face-centered cubic (fcc)-Ag. With the increase of Ag content, the hardness of ZrN-Ag composite film increased rapidly and then decreased rapidly. The maximum hardness value was 22.8 GPa at 6.1at.% Ag. At room temperature, the coefficient of friction (Cof.) of ZrN-Ag films were lower than the ZrN film. During 25-500°C, the Cof. of ZrN-Ag films at 29.16 at.% Ag were lower than ZrN film, while the wear rate were higher than the ZrN film. In summary, the addition of Ag improved the hardness, and decreased the Cof. of the ZrN-Ag during 25-500°C.