Papers by Keyword: Wear Property

Abstract: The surface of 45 steel is quenched by CO₂ laser with scanning speed 1000 mm/min and different laser power 1000W, 1200W, 1400W, 1600W and 1800W. Experiments are carried out to analyze microstructure, friction and wear properties of quenched 45 steel. The results show that the quenching layer thickness increases gradually with the increase of laser power,and the maximum value of quenching layer hardness increases first and then decreases. When the laser power is 1600W, the maximum hardness value is 883HV_0.5. But when the laser power is 1800W, the hardness of quenching layer becomes to decrease. The reason is the surface of 45 steel becomes to melt. The wear volume increases first and then decreases too. When laser power is 1600W, the minimum wear volume is 0.08mm³, which is 6.4% to the wear volume of 45 steel matrix without laser quenching. Therefore, better microstructure and properties of 45 steel can be obtained when laser scanning speed is 1000mm/min and laser power is 1600W.

Abstract: Mechanically ground recycled carbon fibers (rCFs) reinforced polymer composites were investigated in this paper. The rCFs were collected from the woven prepreg waste. The as-received (rCFs-AR) and cyclic cryogenic treated (rCFs-T) carbon fibers were incorporated separately in the epoxy matrix composite. The objective of this study is to study the wear behaviour of the epoxy composites with respect to the as-received and treated rCFs. Prior to the composite fabrication, the surface morphologies of rCFs-AR and rCFs-T were examined with the scanning electron microscope (SEM). It is found that the cryogenic treatment is effective in removing the epoxy resin from the carbon fiber due to the mismatches in the thermal expansion at the interface of rCFs and epoxy. The rCFs-AR and rCFs-T were homogeneously distributed in epoxy resin through ultrasonication. The void-free samples were then fabricated using vacuum casting technique. Micro Pin-on-disc Tribotester (CM-9109) was used to test the tribological behaviour of the polymer composites. The coefficient of friction (CoF) and wear rate of epoxy composites revealed that the reinforcement effect of rCFs-T is better than that of the rCFs-AR as the incorporation of rCFs-T decreases the CoF and improves the wear resistance of epoxy composites in comparison with rCFs-AR. The tribological results clearly showed that the rCFs was a valuable product worth to be reused as reinforcement in the new composite, as the incorporation of treated rCFs was effective in improving the tribological properties of the epoxy composites.

Abstract: The effect of Y addition on the hardness and wear properties of Ni-Mn-Ga magnetic shape memory alloys is researched by means of dry sliding test and Scanning Electron Microscope (SEM) in the paper. The results show that Y addition makes Ni-Mn-Ga alloys become harder, and the hardness of Ni-Mn-Ga shape memory alloys increases with Y content increasing. Adding Y improves the dry-gliding wear property of Ni-Mn-Ga alloy. Main abrasive wear mechanism is observed in Ni-MnGa-Y alloy.

Abstract: The antibacterial agent (LZB-GC) was added to composite resin materials with varied ratio (0.5%, 1%, 1.5%, and 2%) by mechanical and ultrasonic methods. The effects of different contents of the antibacterial agent on the mechanical and fibration properties of the composite resin were measured. The results showed 1.5% group acquired the best flexural strength, and the surface hardness decreased while the friction coefficient increased with improving the antibacterial agent content.

Abstract: We researched and developed the composite polymer materials and products from them, working in conjunction with raw-cotton. It is established that the production of friction pairs of working parts of machines (pegs) made of developed composite polymer materials increases their efficiency and durability to 2.0 -2.2 times.

Abstract: Zn-Al composites with carbonized rice husks were prepared by permanent mould. Microstructure and wear property of Zn-Al composites were measured under the condition of as-cast heated at 375 °C and 430 °C corresponding to solid and semi-solid range. The microstructure of as-cast, heated at 375 °C and 430 °C were different. The microstructure of as-cast Zn-Al alloy revealed primary a dendrites (α) and eutectoid α+η (α,rich Al, η rich Zinc)phases. The microstructure of ZA alloy with carbonized rice husks was fine dendrites for heated at 375 °C and second and third dendrites were almost dispersed. After semi-solid treatment, the microstructure of Zn-Al composites presented quasi-round or round and large with time prolonger. The hardness of Zn-Al composites rose with carbonized rice husks and increased slightly by heat treatment. Wear resistance of Zn-Al composites with carbonized rice husks improved significantly and increased with carbonized rice husks. But at the same amount of carbonized rice husks the wear resistance of the composite varied little regardless of being in the state of as-cast or heat treatment.

Abstract: The oxidation film was prepared by anode oxidation method on ZL101 aluminium surface, its morphologies, compositions and phases were characterized with SEM (Scanning Electron Microscope), optical profiler, EDS (Energy Disperse Spectroscopy), respectively, its friction coefficient and abrasion performance were analyzed by wear test, and its wear mechanism was discussed. The results show that the thickness of anode oxidation layer is about 35-40m, under dry friction condition, sliding friction coefficient is 0.65-0.72, the wear forms are abrasive attrition and adhesion wear, the low friction pair between furrows effect and adhesion effect improves the wear performance of anode oxidation film on ZL101 aluminum alloy surface.

Abstract: A new ZrO₂ nano-composite ceramic tool and die material was prepared with vacuum hot pressing technology. The friction and wear behaviors of ZrO₂ nano-composite ceramic tool and die materials in sliding against 45 chilled steel rings under dry friction were investigated by using an MMW-1A abrasion wear tester. The mechanical properties and the friction and wear properties of the composites with various compositions and contents were studied. It is indicated that the changing trends of the wear rate and the mechanical properties of the composites with the change of TiB₂ and Al₂O₃ contents are roughly the same, but the friction coefficient is not obviously. The friction and wear properties and the mechanical properties are finer when the TiB₂ and Al₂O₃ content is both 10%.

Abstract: In this study, the abrasive testing machine which was similar to the roller mills was used. It used orthogonal test design and cast iron as the wear material. The main factor effected wear results such as abrasive particle size, rotation speed and rolling gap between the metal materials surface of two rollers were considered in order to find out the best value of each factor and optimize the condition of wheat grinding. Furthermore the wear properties of grain powder on cast iron and wear mechanisms were discussed. The results showed that powder size is the most important factor of the wear properties, the gap is the secondary factor and rotation speed is third. The wear loss is minimal while size is 0.2mm, gap is 0.5mm and rotation speed is 181± 2r/min.

Abstract: Polypropylene(PP)/carbon nanotube(CNTs) nanocomposites with different CNTs fraction were prepared by the melting blend method. The effects of CNTs content on the wear properties and mechanical properties were mainly investigated. The results show that the friction coefficient of the nanocomposites decreased as the concentration of CNTs is increased. With increasing CNTs content, tensile strength, ultimate strain, compact strength and Young’s modules increase firstly and then decrease. For the composite with an effective CNTs content of 3 wt, its tensile strength, ultimate strain, compact strength and Young's modules were improved by 72, 44.4,88 and 37 %, respectively, as compared to PP.