EFFECT OF TUNGSTEN CARBIDE ADDITION ON THE WEAR AND MICROSTRUCTURE PROPERTIES OF ALUMINIUM MATRIX BY POWDER METALLURGY ROUTE
Mayank Pardhi, Tribhuwan Kisore Mishra
Gyan Ganga Institute of technology and Sciences, Jabalpur-482003, India
Abstract - The development of light-weight machine components being used in adverse working conditions has always been a challenge. Powder metallurgy is the most significant technique and provides better flexibility in designing the light-weighted component.
In this thesis, the abrasive wear behaviour of aluminum-based metal powder preform was investigated experimentally. Four different metal powders preform viz. Al-0WC, Al-5WC, Al-10WC, and Al-15WC were prepared by powder metallurgy route. Universal Testing Machine was used to prepare these metal powder specimens at a compaction pressure of 80KN. Sintering of green specimen was carried out at 620°C by using an electrical muffle furnace.
The feedstock powders and corresponding sintered metal powder perform were characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), for microstructural studies, elemental analysis, and phase identification. In addition, the hardness and porosity were obtained using Rockwell tester and image-J software.
Pin-on-disc war tester was used to measure the abrasive wear test of sintered metal power preform asperformed using silicon carbide abrasive media (400 μm grit size) fixed on the circular disc of 165mm diameter as per the G 99-5 standard.
Experimental results suggest that the addition of WC improves the mechanical and wear properties. The WC mixed sintered preform possesses a relatively dense microstructure. AL-10WC exhibits higher hardness and it is 33.33% higher hardness than Al-0WC sintered preform. Similarly, AL-10WC sintered preform shows minimum volumetric wear and wear rate, and Al-0WC, Al-5WC, and Al-15WC sintered preform exhibited 99.64, 37.29, and 19.25 % lower volumetric wear as compared to Al-10 sintered preform. In addition, cutting wear mechanisms were seen in AL-WC sintered preform.
Keyword: Aluminum, WC, abrasive wear, hardness, SEM, and porosity.
1 INTRODUCTION
Manufacturing is the process of transforming low-quality raw materials into completed goods. The casting technique is widely used in industries for producing many sorts of components, however, it has the disadvantage of not being suited for intricate shapes and geometry. To preserve the necessary dimension, form, and size, secondary processes such as finishing are required.
Another production method for light engineering machine parts and components is powder metallurgy (P/M).
Powder metallurgy roots can readily make automotive components, aircraft parts, and other complex shape parts with good dimensional accuracy and surface finishing.
1.1Aluminum (Al):-Aluminum is the best material for making light-weight components. It can be found on the earth as cryolite and bauxite. Aluminum has good corrosion and mechanical characteristics. In addition, it's a
substance that's both conductive and corrosion-resistant. Because of these characteristics, it is widely employed in various industries, including aerospace, car, marine, and architectural construction. It's also utilized in transmission lines for electricity.
Aluminum is produced commercially using the Hall–Héroult method.
2 LITERATURE REVIEW
Venkatesan Govindarajan et al., (2021) Investigated the the hardness and wear properties of of titanium alloy mixed with WCmetal powder composite pr by metal powder metallurgy route. Two fifferent percentage 5 and 10 wt% of WC was with titanium alloy. Wear and microhardness was measured by pin-on-disc wear tester and Vickers hardness tester. Author reported that addition of WC imprve the hardness and wear properties. Hardness and weae rate was reports as as476.79 VHN, 13.158 mg/m (×10−3).
K.P.Vetrivel et al., (2017) Investigated, the effect of sliding wear behaviour in Aluminum-WC composites made by stir casting. Three different WC percentages (3 percent, 6%, and 9%) were chosen for research, along with 3%
graphite. Three distinct loads of 10N, 15N, and 20N were used in the wear test, along with three different speeds of 1m/s, 1.5 m/s, and 2 m/s. Wear diminishes as the sliding distance increases, according to the results. As the WC content rises, so does the hardness and wear resistance.
Shreenivas Annigeri et al., (2017) Investigated, The influence of WC concentration nano and micro particles on micro structure and mechanical properties was investigated. 1 percent, 5%, and 10% WC were used to make nano and micro composites, which were then combined in an Al matrix. To produce solid specimens out of metal powder, spark plasma sintering was used. The density and hardness of the material grow as the WC increases. The microstructural characteristics of WC are improved.
Amir Pakdel et al. (2017) Investigated The influence of WC on the mechanical, mechanical, tribological, and microstructural properties of aluminium LM4 was investigated. To determine the wear behaviour of the composite, pin on disc wear testers were utilised, and XRD analysis was performed to determine the presence of various elements matrix. WC enhanced mechanical qualities such as hardness, tensile strength, and impact
strength, as well as tribological and microstructural properties.
3 NEED OF STUDY
This study aims to investigate the wear behaviour of the Al and WC binary systems by analysis of the results of the dry sliding wear testing of the Al-WC powder performs. As there is no direct information available on the validation and identification of the wear rate, volumetric wear and porosity.
The increase in the accuracy of the results and their analysis may be utilized by the design and development and the operation engineers to predict the limiting values in terms of instantaneous wear and in terms of sliding distance and the velocity. The study also investigate the nature of wear. Wear rate and volumetric wear and the effects of the parameters like friction coefficient and the avg. wear with respect to the % WC content in the Al-WC powder preforms. The experimentation shall be carried out on a tribometer of Pin-On Disc type.
4METHODOLOGY AND EXPERIMENTAL WORK
The goal of this chapter is to discuss the methodology used in this present work including powder selection, die punch design. Aluminum (al) and tungsten (w) powders was selected for cylindrical pin specimen preparation. The sample preparation and characterizations wear test was described in this chapter. The outline of this work is shown in Fig. 4.1
Figure 4.1Outlines of Experiments
5 MICRO STRUCTURE SEM/EDS ANALYSIS
The microstructure of AL and WC powder is shown by Fig. 5.1 (a-c). Microstructure exhibits that Al powder possess spherical with elongated structure and WC possess spherical micro structure. When these powder were mixed using ball milling mixture for one hour backward and forward direction WC powder mixed uniform ally with Al powder as shown in Fig. 5.1 (c). Bright portion confirm that WC mixed with al and make dense microstructure.
Fig. 5.1 Microstrucutre of (a) Al (b) WC and (C) AL-WC powder
The SEM images of Al, Al-5WC, Al-10WC, Al-15 WC sintered preform are shown by Fig. 5.2 (a-d) respectively. Gray patches exhibits presence of Al and bright patches exhibits presence of WC. It is also noticed that as percentages of WC increases the microstructure becomes dense and when it is increases beyond 10 % the WC deposited on the upper parts of the preform. It confirm that extra amount above the optimum addition does not observed by metal matrix and this also responsible to increases the brittleness and reduces the hardness of composite.
Pores and micro-cracks are seen in Al- 15WC sintered preform
Fig. 5.2 Microstrucutre of (a) Al, (b) Al- 5WC, (C)Al-10WC and (d) AL-15WC
sintered preform
EDS result of Al-5WC, Al-10WC and Al- 15WC sintered preform (Fig. 5.3) confirmed the presence of various eleents including Aland WC. During sintering soome oxidation also taks pace therefore C and O also seen in EDS of sintered preform.
Figure 5.3 EDS Images of (a) Al-5 WC, (b) Al-10 WC, (c) Al-15WC sintered preform
5.1 Hardness and Porosity analysis The porosity of Al-0WC, Al-5WC, Al-10WC and Al-15WC sintered preform are shown in Fig 5.4 and are 30.25%, 15.25%, 12.64
% and 14.54 %. Image-j software was used to meaasured the porosity by using SEM images. Area percentage counting method was adopted to find out porosity.
Minimum porosity is shown by Al-10WC sintered preform wheres higher porosity is shown by Al-0WC sintered preform.
Additon of WC decreases the porosity but after optimum addition of 10% porosity increases. The increaseing of porosity after optimum addtion is due to amorphu, brittle strucutre. The another reason may be speraton of Alparticles due to extra amount of WC in matrix which increases the porosity.
Figure 5.4 Porosity of (a) Al-5 WC, (b) Al-10 WC, (c) Al-15WC sintered preform The Hardness of Al-0WC, Al-5WC, Al- 10WC and Al-15WC sintered preform are shown in Fig 5.5. Higher hardness is shown by Al-10WC sintered preform. Al- 5WC, Al-10WC and Al-15WC sintered preform exhibited 20.37, 33.33 and 25.92
% higher hardness as compared toAl-0WC sintered preform. The Higher hardness of Al-10WC sintered prefom is attributed dense microstrucutre.The Al-10WC sintered preform shows lower hardness due to higher orosity.
Figure 5.5 Hardness of (a) Al-5 WC, (b) Al-10 WC, (c) Al-15WC sintered preform
5.2 Wear and coefficient of friction analysis
Abrasive wear behaviour of sintered specimens in contradiction of a silicon carbide abrasive media having 400 μm sized consist of angular shape are shown in Figure 5.7. Volume loss method was adopted to measure the wear using following formula. The schematic diagram of volumetric loss of cylindrical specimen is shown by Fig. 5.6.
𝑉𝑤𝑒𝑎𝑟 =𝜋
4× 𝑑2× ℎ
Figure 5.6 Volumetric loss of cylindrical specimen
d- Diameter of cylindrical specimen(mm) h- high loss (μm)
V- Volume loss
The volumetric wear of Al-0WC, Al- 5WC, Al-10WC and Al-15WC sintered preform are shown in Fig 5.7 and are 0.00151, 0.001038, 0.000756and 0.000902mm3 respectively. The result shows that Al-10WC sintered preform shows minimum volume loss and maximum volume loss is shown by Al- 0WC sintered spcimen. Al-0WC, Al-10WC and Al-15WC sintered preform exhibited 99.64, 37.29 and 19.25% lowere volumetric wear as compared to Al-5WC sintered preform.
Similarlly The wear rate (mm3/Nm) of Al-0WC, Al-5WC, Al-10WC and Al- 15WC sintered preform are shown in Fig 5.8 and are 0.00151, 0.001038, 0.000756and 0.000902mm3 respectively 1.51×10-3, 1.03×10-3,7.56×10-4 and 9.02×10-4 respectively. Al-10WC sintered preform shows minimum wear rte.
Minimum volumetric loss and wear rate is attributed to higher hardness, dense microstructure and minimum porosity.
Figure 5.7 Volumetric wear of sintered specimens
Figure 5.8 Wear rates of sintered specimens
Coefficient of friction of sintered specimen is shown by Fig. 5.9. Initially coefficient of friction shows increasing trend due to less contact area between sample and abrasive media. As sliding distance increases the area between sample and abrasive media increases than coefficient of become stable. Another reason of increasing coefficient of friction is removal of material due to penetration of angular shape carbide particles on the surface. its result increasing of temperature on the interface which promote formation of oxide layer which prevent further wear and coefficient of friction become stable. Al-0WC exhibits lower coefficient of friction and Al-5WC exhibits higher coefficient of friction.
Figure 5.9 Coefficient of friction of sintered specimens
5.3 Worn-out surface analysis
Analysis of worn-out surface helps to identified wear mechanism and mode of wear on the surface. SEM images was used to investigate worn out surface of sintered wear out specimens and shown by Fig 5.10 (a-d). In Al-0WC material removed due to fracture of al particle.
Large amount of material removed from the surface of AL-0WC specimen due to lower hardness and less porosity. In Al- 5WC sample small comparatively lessdeep grove can be seen and material removed due to cutting. In Al-10WC sample less amount of material removed from the surface during wear due to higher hardness and minimum porosity. Deep groove is visible in sintered WC-15WC surface along with carbide penetrate on the surface during wear large amount of material removed from the surface and material removed due to cutting. These result indicated that addition of WC on Al metal powder composite decreases the wear and addition of 10 WT % of WC is optimum.
Figure 5.10 SEM images of worn-out surface of (a) Al-5 WC, (b) Al-10 WC, (c)
Al-15WC sintered preform
To examine more logical features of the worn-out surface of worn-out surface of sintered specimen 3-D morphology was used. The worn-our surface of sintered of texture specimen is shown by 3-D morphology in figure 5.11 (a-d). Which confirms that small grooves and pits of in Al-10WC sintered specimen. In addition, deep grooves and micro-cracks are clearly seen in the 3-D morphology of WAl-5WC and AL-15WC sintered specimen. Which also confirms the elimination of a large number of Al particles from the surface the AL-0WC Sintered specimen. The dark green region displays the presence of contours in a valley, and the blue region displays peaks.
6 CONCLUSION
From the experiment result following conclusions were finding out of Al-WC Metal powder composite.
1. Addition of WC makes powder structure dense whereas Al powder
possess cooperatively porous structure.
2. SEM images conforms that WC informally distributed informally in AL matrix. Al-10WC sintered specimen possesses dense microstructure which confirms that
addition of WC makes
microstructure dense. EDS result confirms presence of Al, WC as a major elements.
3. Addition of WC decreases the porosity and increases the hardness.
AL-10WC exhibits minimum porosity and higher hardness. Al- 5WC, Al-10WC and Al-15WC sintered preform exhibited 20.37, 33.33 and 25.92 % higher hardness as compared to Al-0WC sintered preform.
4. Al-0WC, Al-5WC and Al-15WC sintered preform exhibited 99.64, 37.29 and 19.25% lowere volumetric wear as compared to Al-10WC sintered preform.
5. The wear rate (mm3/Nm) of Al-0WC, Al-5WC, Al-10WC and Al-15WC sintered preform are 0.00151, 0.001038, 0.000756 and 0.000902 mm3 respectively 1.51×10-3, 1.03×10-3, 7.56×10-4 and 9.02×10-4 respectively. Al-10WC sintered preform shows minimum wear rate.
Minimum volumetric loss and wear rate is attributed to higher hardness, dense microstructure and minimum porosity.
6. Al-0WC exhibits lower coefficient of friction and Al-5WC exhibits higher coefficient of friction.
7. AL-0WC sintered specimen shows fracture wear mechanism whereas cutting wear mechanism is seen in WC added specimen.
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