Papers by Author: Fu Shan He

Abstract: Bamboo fiber reinforced resin matrix brake materials were selected as research object, dry and wet friction experiment was conducted on MM200 abrasion tester. Results show that: friction coefficient drops down to a very low level under wet condition, wear rate of samples and counterparts also decreases, but the values of friction coefficient are still in the range of dry friction. Under dry and wet conditions, the tribilogical performance of sample has different relationships with the pressure and speed, especially with the speed. Friction surface was lubricated and cooled by water, in the meantime, the formation of friction film is suppressed, which leads to the differences of the tribilogy performance between dry and wet conditions. Morphologies of fricion surface was observed by SEM, worn surface in wet braking was not covered by friction film, many fine cracks and some patches were scattered over the substrate.

Abstract: In this paper, a novel no-asbestos brake composite reinforced by natural bamboo fibers is studied. The bamboo fibers are modified by heat treatment, alkali treatment and coupling treatment respectively. Tribological performance of different fibers reinforced composites are developed by means of friction test and microstructure observation. The results show that heat treatment of bamboo fibers at 140 for 4 hours makes the friction and wear characteristics of brake composites more stable than the untreated ones, but poor wear resistance at low temperature and heat fade still exist. There is no significant change on fiber surface. The alkali treatment of 17% NaOH solution for 12 hours contributes to desirable combination of higher friction coefficients and lower wear rates, and the surface morphology shows a number of deep grooves that avail the interface bonding. The effect of coupling treatment with KH550 on tribological performance of composites have the similar rule to that of the alkali treated ones except of heat fade, and the fiber surface is evenly coated with the coupling agent, which enhances the bonding of fibers and resin but fails at elevated temperature.

Abstract: In this paper, effects of solid solution treatment temperature on microstructure and tensile properties of casting SAF 2507 super duplex stainless steel were researched by means of optical microscope (OM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and tensile test. The results indicate that the amount of γ phase increases according to a linear relationship f(g ) = -0.134T +159.94 during the temperatures from 1100°C to 1250°C. Tensile properties of casting SAF 2507 super duplex stainless steel fluctuate with solution temperature change. Austenitic grain size and morphology are the most important factors on tensile property. The tensile strength is the highest owing to the finest austenitic grain at the solution temperature of 1150°C. The elongation is related to the fracture mode. At 1100 , elongation ration is highest because of the ductile fracture.

Abstract: SAF2906 is a new kind of super duplex stainless steel, and more corrosion-resistant and strong than SAF2507, suitable to be used in the low temperature and corrosion conditions. In order to prevent the occurrence of microstructure changes resulting in the property deterioration, in the general, the castings made for SAF2906 should be cryogenically treated before they are used in the ultra low conditions. N is an alloying element, usually added to stainless steels to increase the material properties. So, In this paper, the effects of N content on microstructure, mechanical and corrosion resistance properties of SAF2906 casting super duplex stainless steel (SDSS) after cryogenic treatment were studied by means of Optical Microscope(OM), X-ray Diffraction(XRD) and electrochemical workstation. The results indicate that N can increase the amount of γ phase according to a linear relationship of Φ(γ)=99.4×w(N)+6.16. When N content is low or medial, γ phase can precipitate from ferrite. When N content is high, γ phase does not precipitate from ferrite and is converted directly from ferrite and austenite grain boundaries. The higher N content, the greater tensile strength and elongation, the better corrosion resistance. Compared with solution state, cryogenic treatment can improve corrosion resistance.