scholarly journals Microstructure and Properties of AA6061/SiCp Composites Sintered under Ultra High-Pressure

2020 ◽  
Vol 10 (20) ◽  
pp. 7363
Author(s):  
Lei Xu ◽  
Erkuo Yang ◽  
Yasong Wang ◽  
Changyun Li ◽  
Zhiru Chen ◽  
...  

Ultra high-pressure sintering (UHPS) was used to prepare AA6061/SiCp composites with different contents and the effect of sintering temperatures on microstructure and mechanical properties was investigated in this study. The results showed that a uniform distribution of nano-SiC particles (N-SiCp) is obtained by the UHPS method. With the increase in N-SiCp contents, the higher hardness and better wear resistance could be inspected. The interfacial reactions and Al4C3 phase appeared above 550 °C. The relative density of composites first increased and then decreased; with the temperature raising it reached 99.58% at 600 °C. The hardness and wear property showed the same trend with the hardness reaching 52 HRA and wear rate being 1.0 × 10−6 g/m at 600 °C. Besides, the wear mechanism of the composites is mainly composed of abrasive wear and adhesive wear.

2020 ◽  
Vol 10 (15) ◽  
pp. 5107 ◽  
Author(s):  
Changyun Li ◽  
Yasong Wang ◽  
Lei Xu ◽  
Yang Liu ◽  
Ningning Lu ◽  
...  

Graphite/6061 aluminum (G/6061Al) composites with different content of graphite were ultra-high pressure (UHP)-sintered and hot pressing (HP)-sintered, respectively. The result shows that homogeneous dispersion of graphite flakes in the 6061Al matrix can be achieved using graphite flakes coated by nano-Al particles, both in the UHP-sintered and in the HP-sintered composite. Due to the comprehensive effects of ultra-high pressure, high temperature and formation of Al4C3, the UHP-sintered composites endowed with higher relative density, higher hardness, stronger tensile strength and better wear resistance than the HP-sintered composite. The highest tensile strength of the UHP-sintered with 5 vol.% graphite is 183 MPa. Wear test reveals that the wear rate of the UHP sintered with 10 vol.% G/6061Al decreases drastically when the sintering temperature is 650 °C or higher, which is one to three orders of magnitude lower than that of the HP-sintered. The lowest wear rate of the UHP sintered with 10 vol.% graphite is 0.15 × 10−5 g/mm, while that of the HP-sintered composite is 133 × 10−5 g/mm.


1983 ◽  
Vol 27 ◽  
Author(s):  
W.C. Oliver ◽  
R. Hutchings ◽  
J.B. Pethica ◽  
I.L. Singer ◽  
G.K. Hubler

ABSTRACTOne measure of the surface mechanical properties of materials can be obtained through microhardness data. The success of microhardness in predicting the improvements in wear resistance of ion implanted metals has been mixed. In this paper the cases of N implantation into 304 S.S. and Ti implantation into 52100 bearing steel will be examined. Microhardness data indicates little or no hardness changes whereas large wear rate changes are observed. From these two examples it is clear that the wear mechanism, the chemical nature of the surface, the ductility, and the toughness can be more important than the hardness changes.


2015 ◽  
Vol 1095 ◽  
pp. 135-139
Author(s):  
Wei Xi Shi ◽  
Cheng Wu Du ◽  
Gui Mao Li ◽  
Zhi Ming Liu

The morphology of eutectic and primary silicon phases was analyzed by OM and SEM. OM and SEM results show that pure Nd can significantly refine both eutectic and primary silicon of hypereutectic Al-20%Si alloy. Morphology of primary silicon is transformed from star-shaped and irregular morphology to fine polyhedral and grain size of primary silicon is refined from 80~120 μm to 20~50 μm. Friction and wear resistance tests show that friction coefficient of Al-20%Si alloy reduces after Nd modification. Wear resistance of Al-20%Si alloy after modification is significantly improved as compared to the initial sample. The dominant wear mechanism for 0.3% Nd modified alloy is abrasive wear, adhesive wear and oxidative wear mechanism, but wear mechanism for unmodified alloy is abrasive wear and adhesive wear mechanism.


2021 ◽  
Vol 57 (1) ◽  
pp. 97-104
Author(s):  
D.-B. Wei ◽  
X. Zhou ◽  
F.-K. Li ◽  
M.-F. Li ◽  
S.-Q. Li ◽  
...  

To improve the wear resistance of ?-TiAl alloy, Ta alloy layer was prepared on surface by double glow plasma surface alloying technique. The tribology behavior of Ta alloy layer against Si3N4 at 25?, 350? and 500? were comparatively studied. The results showed that Ta alloy layer comprised a deposition layer and a diffusion layer. The deposition layer played a role in protection as a soft film. With the increase of temperature, the wear mechanism of ?-TiAl changed from abrasive wear to coexistence of abrasive wear and oxidation wear. Ta alloy layer?s wear mechanism changed from adhesive wear to coexistence of adhesive wear and oxidation wear. Surface Ta alloying process significantly reduced the wear volume, the specific wear rate and the friction coefficient of ?-TiAl and improved the wear resistance properties of ?-TiAl.


2015 ◽  
Vol 817 ◽  
pp. 571-576
Author(s):  
Jun Tao Zou ◽  
Chan Wang ◽  
Yang Li ◽  
Xian Hui Wang ◽  
Shu Hua Liang

The effect of ambient temperature, materials state and lubrication condition on wear resistance of Cu10Al5Fe5Ni alloy was investigated. The wear surface morphology was characterized by a scanning electron microscope (SEM), and the wear mechanism was discussed as well. The results show that the friction coefficient of Cu10Al5Fe5Ni alloy increases and then decreases with increasing temperature. The wear rate of the Cu10Al5Fe5Ni alloy after solid solution and ageing treatment is less than that of the as-cast alloy, and the wear rate of Cu10Al5Fe5Ni alloy reduces dramatically from 5.31×10-5 mm3 / (m· N) into 1.80×10-6 mm3 / (m·N) after adding lubricating oil. At elevated temperature, the prior wear mechanism is the fatigue wear, accompanying by slight abrasive wear and adhesive wear for the aged Cu10Al5Fe5Ni alloy.


2020 ◽  
Vol 30 (5-6) ◽  
pp. 195-202
Author(s):  
Vincent C. Ezechukwu ◽  
Chukwuemeka C. Nwobi-Okoye ◽  
Philip N. Atanmo ◽  
Victor S. Aigbodion

The numerical approach for the study of wear performance of breadfruit seed shell ash particles (BFSAp) and Sodium hydroxide (OH)/silane (APS)functionalized Momordica angustisepala fiber (MAf)/epoxy hybrid composites were investigated. The MAf fibers were treated with an OH-APS solution. Hardness values, wear rate and wear mechanism of the samples were determined. A 65.82% improvement in wear resistance was obtained at the load of 30N of 30wt%MAf-20wt%BFSAp composite. The wear rate and wear damage followed in this order: epoxy(matrix)˂epoxy/30wt%MAf-20wt%BFSAp˂epoxy/OH-APS treated 30wt%MAf-20wt%BFSAp composites. The wear mechanism observed in this work is a combination of abrasive and adhesive wear. High wear resistance was obtained in epoxy/OH-APS treated 30wt%MAf-20wt%BFSAp composites.


Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4343
Author(s):  
Yun Zhang ◽  
Richen Lai ◽  
Qiang Chen ◽  
Zhen Liu ◽  
Ruiqing Li ◽  
...  

In this study, four kinds of heat treatments were performed to obtain a certain amount of retained austenite, which can result in good toughness and low brittleness accompanied with wear resistance of an in situ VC particle reinforced iron-based composite (VCFC). Microstructure, mechanical properties and wear resistance of the samples under heat treatment of QP, QPT, MQP and MQPT were compared. The experimental results indicated that there is a huge difference in microstructure between MQPT and the other heat treatments. High-proportion retained austenite and white net-like precipitates of M7C3 carbide existed in the MQPT-treated sample, but thick M7C3 carbide with brittleness was discovered in the other sample. Thereby, high-proportion retained austenite contributed to its low hardness of 634 HV and high tensile strength of 267 MPa, while a maximum hardness of 705.5 HV and a minimum tensile strength of 205 MPa were exhibited in the QPT-treated sample with a V-rich carbide of high hardness, a Cr-rich carbide of brittleness and a high-proportion martensite. Meanwhile, a phase transformation from retained austenite to martensite could increase the hardness and enhance wear resistance based on the transformation-induced plasticity (TRIP) effect; its wear rate was only 1.83 × 10−6 mm−3/(N·m). However, the wear rates of the samples under QP, QPT and MQP heat treatments increased by 16.4%, 44.3% and 41.0%, respectively. The wear mechanism was a synergistic effect of the adhesive wear mechanism and the abrasive wear mechanism. The adhesive wear mechanism was mainly considered in the MQPT-treated sample to reduce the wear rate attributed to high-proportion retained austenite and the existence of wear debris with a W element on the surface of the wear track. However, the abrasive wear mechanism could exist in the other samples because of a lot of thick, brittle M7C3, thereby resulting in a higher wear rate due to immediate contact between the designed material and the counterpart.


2020 ◽  
pp. 306-308
Author(s):  
V.S. Bochkov

The relevance of the search for solutions to increase the wear resistance of bucket teeth of excavating machine type front shovel is analyzed. The reasons for the wear of the teeth are considered. It is determined that when excavating machines work for rocks of VIII and IX categories, impact-abrasive wear of the inner side of the teeth and abrasive external wear occurs. It is proved that the cold-work hardening of Hadfield steel (the teeth material), which occurs during the excavating machine teeth work in the rocks of VIII and IX categories, reduces the impact-abrasive wear rate on the inner side of the teeth and does not affect the abrasive wear of the outer. The methods for thermomechanical treatment of the outer side of the excavating machine tooth is proposed. It can increase the wear resistance of Hadfield steel (110G13L) up to 1.7 times and lead to the self-sharpening effect of the tooth due to equalization of the wear rate of the outer and inner parts of the tooth. The efficiency factor of thermomechanical treatment to reduce the of abrasive wear rate of Hadfield steel is experimentally proved.


2015 ◽  
Vol 98 (12) ◽  
pp. 3782-3787 ◽  
Author(s):  
Bin Liang ◽  
Zhihua Yang ◽  
Jiancun Rao ◽  
Delong Cai ◽  
Xiaoming Duan ◽  
...  

Author(s):  
Fathima Banu Raza ◽  
Anand Kumar

The o-rings in ball retained overdentures deteriorate with time and need replacement to restore the retentive quality. We evaluated retrospectively the mechanical properties of o-rings after 3 years in function in one and two-piece implant-supported overdentures. The o-rings were retrieved from one-piece (Myriad snap, Equinox-Straumann, 3.3 x 13mm) and two-piece (Neo Biotech, 3.3 x 13mm) implant-supported overdenture patients. A total of 16 pairs of matrices were tested for wear, type of damage and elasticity using Pin on Disc method, USB Digital Camera in 30x zoom and Universal Tensile Machine respectively. The statistical analysis for independent groups were done with the Mann-Whitney U test. Assessment of used O-rings showed 84% more wear in the two-piece system with an abrasive type of damage while 46% wear in the one-piece system with a compressive type of damage. The o-rings in one-piece system showed increase in elongation and maximum displacement to 2% and 7% respectively, while two-piece system showed decrease in elongation and maximum displacement by 13% and 6% respectively. In one-piece system, the loss of retention was more with slow wear rate and in two-piece system, the wear resistance of O-rings decreased due to increased stiffness. Further studies to evaluate the changes in O-ring with increased sample size and at interval 1 year will pave way for insight into the progressive changes in the mechanical properties of an O-ring.


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