WEAR CHARACTERIZATION OF LM29 ALLOY WITH40 MICRON SIZED B4C REINFORCED METAL COMPOSITES

This paper deals with the fabrication and evaluation of wear properties by introducing40 micron size B4C particulates into LM29 alloy matrix. LM29 alloy based metal matrix composites were prepared by stir casting method. 3, 6 and 9 wt. % of 40 micron sized B4C particulates were added to the base matrix. For each composite, the reinforcement particles were pre-heated to a temperature of 600 degree Celsius and then dispersed in steps of two into the vortex of molten LM29 alloy to improve wettability. The Micostructural study was done by using Scanning Electron Microscope (SEM), which revealed the uniform distribution of B4C particles in matrix alloy, EDS analysis confirmed the presence of B4C particles in the LM29 alloy matrix.A pin-on-disc wear testing machine was used to evaluate the wear loss of prepared specimens, in which a hardened EN32 steel disc was used as the counter face. The results revealed that the wear loss was increased with increase in normal load and sliding speed for all the specimens. The results also indicated that the wear loss of the LM29-B4C composites were lesser than that of the LM29 matrix. The worn surfaces and wear debris were characterized by SEM microanalysis.

Tribological behaviour of lamb bone ash and boron carbide reinforced ZA-27 hybrid metal matrix composites under dry sliding conditions

This study aims to investigate the tribological behaviour of lamb bone ash (LBA) and boron carbide (B4C) reinforced ZA-27 hybrid metal matrix composites fabricated using a stir casting process. The weight percentage of LBA and B4C particles in the composites were varied from 0-5 wt.%. The composites have been evaluated for density, porosity and microhardness before tribological testing. Dry sliding friction and wear behaviour of composites were studied on a pin-on-disc tribometer by varying load from 10-50 N at a fixed sliding speed of 1 m/s. Also, to investigate the effect of sliding speed on friction and wear behaviour of composites, tests were carried out at 2 m/s and 3 m/s of sliding speed. A scanning electron microscope (SEM) was used for examining the microstructure and worn surface morphology of composite samples. SEM micrographs revealed the presence and homogeneous distribution of reinforcement particles, and energy-dispersive X-ray spectroscopy (EDS) analysis confirmed the presence of LBA and B4C particles in the composites. Composites density decreased, and porosity increased with the addition of reinforcement particles. The microhardness of the 5 wt.% reinforced LBA composite improved by 18.38%, whereas hybrid composite containing (2.5 wt.% LBA + 2.5 wt.% B4C) showed an improvement of 42% compared to the base alloy. The coefficient of friction (COF) and wear loss increased with the increase in load, whereas COF decreased and wear loss increased with the increase in sliding speed. Composites showed superior wear resistance even at higher loads and sliding speeds. SEM micrographs of worn surface revealed adhesion and abrasion type of wear mechanisms. Therefore, with the improvement in wear resistance this developed composite can be used as a bearing material over monolithic ZA-27 alloy in the automotive sector.

Ytterbium impulse laser for surface modification of tool steel with B4C-Al powders

The paper deals with a new application solution of Ytterbium Picosecond Pulsed Fiber Laser for surface modification of 3Kh2V8F hot-work tool steel (the analog of AISI H21 steel). Surface modification was conducted by B4C-Al powders from preplaced pastes followed by laser heating. The ratio of B4C-Al powders was taken as 5/1 by weight and the paste thickness was approximately 1 mm. Laser treatment was conducted according to the following parameters: 1070 nm of wavelength, 100 W of power, 1 mJ of pulse energy, 100 ns pulse duration, pulse frequency range from 50 kHz to 90 kHz. Several tracks with different widths were obtained as a result of treatment depending on velocity of the laser move. EDS analysis showed that B4C particles were not completely dissolved in the weld beads. However, an enhanced concentration of boron (8-12 wt.%) was revealed in the vicinity of B4C particles. The aluminum concentration was low (up to 0.79 wt.%) on the surface of the weld beads.

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.

Mechanical and Tribological Characteristics of Aluminium 2618 Matrix Composite Reinforced with Boron Carbide

Aluminium-based alloys are mainly used for bearing and automotive applications, resulting in more wear and tear of the material. Boron Carbide (B4C), hard ceramic materials used as reinforcement in Al2618 matrix material, was fabricated using the stir casting method. The presence and distribution of the B4C particles were confirmed by X-ray diffractometer (XRD) and Scanning Electron Microscopy (SEM). Taguchi’s design of experimental approach was employed to study the wear characteristics using the L27 orthogonal array. Optimization of parameters like applied load (20, 30, and 40 N), sliding distance (400, 600, and 800 m), and sliding speed (1.25, 2.51, and 3.76 m/s) were done using Signal-to-Noise ratio analysis and Analysis of Variance (ANOVA). Results revealed that speed (46.77%) had more influence on wear behavior, followed by sliding distance (34.74%) and load (9.81%). SEM images of the worn-out composite specimens exhibited an adhesive type of wear mechanism with deep grooves from hard B4C particles.