Papers by Author: Jing Pei Xie

Abstract: In this paper, the Cu/MoS2/Mo composites were prepared by the powder metallurgy technology. The friction wear test was tested by the HST-100 High Speed Electric-tribometer. The microstructure and wearing surface morphology were examined by SEM and EDS. The electrical sliding wear behavior of the composites was discussed. The results indicated that the dense composites are obtained; the wear mechanisms of Cu/MoS2/Mo are mainly abrasive wear and adhesive wear with arc erosion; the effects of current intensity and sliding velocity on the wear property of the composites are complicated, and the composites show the best property when the current intensity is 60A and the sliding velocity is 40m/s.

Abstract: The influences of non-mentallic inclusions on the quality and properties of the steel are depended not only on the quantity of inclusions, but also on the type、shape、size、deformation behavior and distribution condition. The effects of lanthanide rare earth(RE) on the shape、size and distribution condition of inclusions in large rudder arm steel casting is investigated. It was proved that the shape and distribution of inclusions could be improved in the large rudder arm steel casting, and the plastic and toughness of the steel can be increased obviously by the rare earth modification. By means of ANSYS finite element analysis software, the stress field distribution around matrix was simulated, and the reaction mechanism of inclusions by modification was clarified.

Abstract: In this paper, the WC and high-Cr Cast Iron layer were obtained on the surface of ZG30Cr steel by casting-penetrating process, the organization and wear properties of penetrating layer were studied. The results show that the layer is dense, without pores, slag and other defects, the penetrating layer and substrate are metallurgical bonding. When 20 %WC and 80 % Cr-Fe with are added to permeability agent, the penetrating layer has the best wear resistance, is 11.3 times the matrix materials.

Abstract: The erosion wear experiments of low-chromium cast iron containing nickel were done by MCF-30 Erosion Abrasion Experimental Machine. The structure and surface morphology after erosive wear were analyzed by SEM and XRD. The results indicated that the distribution of carbide was reticular after tempering at 250and oil quenching at 960. The maximal erosion wear rate was appeared at 60 °erosion angle, high acid corrosion media have great influence on the abrasion resistance of experimental material and corrosion effects almost had no influence on the abrasion resistance of experimental material in the weak acid environment of pH≥3. The erosive wear mechanism of the experimental material was studied.

Abstract: In order to improve the wear resistance of continuous casting crystallizer, Co-based alloy coatings were prepared on copper substrate by a pulsed Nd:YAG laser. Scanning electron microscopy, X-ray diffraction, microhardness and wear resistance testing were employed to study the microstructure and properties of the cladding coatings. The results show that the friction coefficient and wear mass loss of the cladded coating with the volumn ratio of Stellite X-40：TiC：CaF2=60：10：30 are both the smallest; the average microhardness of the cladded coating is 496.2HV0.2 which is about five times higher than that of the substrate.

Abstract: Using sub-micron WC/Co metal ceramic composite as coating materials for laser alloying experiments to prepare high hardness and wear resistance alloyed layer on the surface of 9CrSi. The microstructures of laser-alloyed coating were detected by SEM and XRD. The microhardness and wear-resistance of the coatings were also investigated. The results indicate that, the laser alloyed layer and substrate form a good metallurgical bonding. The analysis of SEM reveal that the alloyed layer can be divided into alloyed zone, heat affected zone and substrate zone. The alloyed zone is composed by martensite, netted dendrite carbides and small carbide particles, the netted dendrite carbides distribute in the martensitic and the small carbide particles dispersed in the gap of the netted dendrite. The heat affected zone is consisted of retained austenite and martensite. There is no significant change in the matrix zone.The coating has a high hardness of 900HV0.2 , and the abrasion loss of the alloyed coating is just one ninth of that of 9CrSi. The wear resisitance of the alloyed coating relative to the substrate 9CrSi has significantly improved.

Abstract: A ductile iron coated with metal-matrix pastes containing hard phase TiC and CrxCy was laser alloyed by an Nd: YAG laser and a CO2 laser. The microstructure, composition and wear resistance were analyzed by scanning electron microscopy (SEM), incorporating energy dispersive spectrum (EDS), X-ray diffraction analysis (XRD) and friction wear tester respectively. Results revealed that the alloyed area was composed by alloyed zone and heat affected zone. The microstructure of the alloyed layer was significantly influenced by the laser beam kind. Finer grains and fewer cementites were contained in the alloyed layer produced by Nd: YAG laser. Friction and wear experiments showed that the alloyed layer had better tribology properties.

Abstract: Rapidly solidified hypereutectic Al-21Si was prepared by the single roller melt-spinning technique. The microstructure morphology characteristics and phase structures of the alloy were characterized using SEM, TEM and XRD technique. The results showed that the grains were refined and the micro-nano composite structures were formed under rapid solidification. The microstructure of the Al-21Si alloy was composed of micro-nanostructured α-Al phase and feather-needle-like eutectic α-Al+β-Si phase. The α-Al phase was the leading phase in the eutectic α+Si phase. The nucleation and growth of primary silicon are suppressed and primary silicon could not be precipitated. The hypereutectic Al-21Si alloy showed the hypoeutectic solidification microstructure. Wear resistance was improved obviously when the rapidly solidified and was five times higher than that of the traditional casting alloys.

Abstract: Nickel-based nano self-lubricating coatings were deposited on medium carbon steel by laser. The microstructure and tribological properties of the typical coating containing 10wt % nano-hBN powders were investigated using SEM incorporating EDS, and high temperature tribo-tester, respectively. It was found that the cladding layer and substrate was good metallurgical bonding. Dry sliding frictional tests suggested that the composite coating containing about 10wt % hBN powders has lower friction coefficient than that of pure Ni60 cladding at room temperature with a load of 40N and a speed of 2m/s, as well as 400°C with a load of 20N and a speed of 2m/s. The wear resistance of Ni60-hBN coating is about 10 times than that of Ni60 coating. The SEM analysis of the abrasion morphology found that wear mechanism of self-solid lubrication coating was adhesive wear, and wear mechanism of the cladding layer of non-lubricant was adhesive wear with abrasive wear.

Abstract: The wear resistance, corrosion resistance, high temperature resistance layers were prepared on the surface of ductile iron via laser alloying process, using the mixed ponder of sub-micron carbides power as starting materials. The microstructures of the different laser alloying layers were characterized by XRD, SEM, EDS, TEM. The microhardness and wear resisitance of the laser alloying layers were examined. The results reveal that the flat alloyed coating combines metallurgically with the substrate. the laser area was composed by alloyed zone ,heat-affected zone and matrix zone. The alloyed zone was composed mainly by ledeburite and carbide, while martensite and retained austenite were contained in the heat affected zone, there is no significant change in the Matrix zone. Under conditions that the laser power, spot diameter remain unchanged, with in 400 ~ 1000 mm/min scanning speed, the hardness of alloyed coating increases with increasing scanning speed. The weightlessness of the alloyed samples under the dry sliding friction is one-sixteenth of ductile iron. The wear resisitance of the alloyed coating has improved significantly.