Advanced Materials Research Vols. 139-141

Abstract: A linear and high molecular weight poly(phenylene sulfide) (PPS) was synthesized from P-dichlorobenzene (P-DCB) and anhydrous sodium sulfide in N-methyl pyrrolidone (NMP), and the High Temperature Gel Permeation Chromatography (HTGPC) technique was utilized to investigate the effects of reaction condition on PPS chain propagation. The experiment results indicated that the high pro-reaction temperature or high post-temperature would interfere with PPS chain propagation, and post-reaction time was another important factor to influence PPS molecular weight (Mw) extension. Furthermore, the optimized ratio of high Mw PPS polymer synthesis was typically at 3-6% molar excess of Na2S over p-dichlorobenzene, and N-methyl-2-pyrrolidone (NMP) were beneficial to the production of high Mw PPS due to the formation of sodium 4-(N-methylamino) butanoate (SMAB). The alkaline reagents such as Na3PO4 and K3PO4 et al could capture the H of -SH, which changed -SH into -SNa and promoted the chain growth of PPS to achieve extension.

Abstract: The siliconized layer was pulse electrodeposited on grain oriented low-silicon steel sheet substrate in KCl-NaCl-NaF-SiO2 molten salts and the influence of duty cycle on the composition and microstructure of the siliconized layer was investigated. The results showed that when the duty cycle was in the range of 10% to 50% at average current density 30mA/cm2, Si content of siliconized layers was similar and the thickness of the layer was did not change much with different duty cycle. Cross sectional observation revealed that the siliconized layers had a two-layer structure. The top layer composed of columnar grains and a transition layer with equiaxed grains was close to the substrate. The layer was unsmooth when the duty cycle was 10%. While the surface appeared smooth and dense and the grains were fine when the duty cycle were 20% and 30%. The layer became more porous as the duty cycle increased to 40% and 50%.

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.

Abstract: The effects of high intensity ultrasonic melt treatment on the microstructure of magnesium alloys were investigated in this paper. Magnesium melts were treated with power ultrasonic wave and then cooled to a predetermined temperature. With the increase in ultrasonic power, the structure exhibited refined and spheroidzed crystal grains. After further increasing the ultrasonic power, the grains tended to somewhat coarsened. Increasing the ultrasonic processing time led to a grain refinement of magnesium alloy.

Abstract: The machining process of titanium alloys always need special control by using coolant and lubricant as it is one of the difficult-to-cut materials. To achieve green cutting of titanium alloy Ti-6Al-4V with water vapor cooling and lubricating, a minitype generator is developed. Compared to dry and wet cutting, the using of water vapor decreases the cutting force and the cutting temperature respectively; enhances the machined surface appearance. Water vapor application also improves Ti-6Al-4V machinability. The excellent cooling and lubricating action of water vapor could be summarized that water molecule has polarity, small diameter and high speed, can be easily and rapidly to proceed adsorption in the cutting zone. The results indicate that the using of water vapor has the potential to attain the green cutting of titanium alloy instead of cutting floods.

Abstract: The aluminizing treatment on the surface of commercial pure copper with addition of rare earth compound CeCl3 was carried out. The followed internal oxidation of the aluminized copper was also carried out in the industrial nitrogen gas flow. The influences of the aluminizing and internal oxidization processing time on the thickness, hardness profile and microstructure were investigated. Results show that the addition of rare earth oxide CeCl3 has great accelerating effect on the aluminizing and internal oxidation processing. The hardness of the surface Al2O3 dispersion hardened copper composite layer by means of internal oxidation with addition of rare earth compound is higher than that of the without addition. The internal oxidation mechanism of the aluminized layer on copper matrix is comprehensive processes of the oxygen inner-toward diffusion and localized internal oxidation of the inner-toward diffusion of aluminum.

Abstract: This article introduces an arithmetic approach to establish an optical system aiming to eliminate the shortcomings in the steel making technique. The current basic oxygen furnace technique is flawed because the level of carbon content in the molten iron is estimated by the workers observation through experience. It is hard to compare, measure and control. The proposed model, on the other hand, is much more computable: relevant data is collected from spectrum distribution during the process of basic oxygen furnace. It predicts the end-point of BOF relatively accurate because spectrum is quantifiable, and the changing process of the furnace flame is essentially the changing process of the spectrum. In this model, we can measure the temperature of the molten steel by the Flame emission spectroscopy theory principle. Further more, the result of the experiment conducted based on the model shows that the model meets the requirements of endpoint judgment online.

Abstract: Semi-solid A356 alloy slurry grain-refined by Al-La master alloy is prepared by low superheat pouring. The effects of La on the morphology and size of primary grain in semi-solid A356 alloy are researched. The results indicate that the semi-solid A356 alloy slurry with particle-like and rosette-like primary grains can be prepared by low superheat pouring. The size and morphology of the primary grain in semi-solid A356 alloy are markedly improved by La. The refining mechanism of La on the morphology and size of the primary grain in semi-solid A356 alloy is delved. The eutectic reaction of Al-La binary alloy provides the effective nuclei for formation of the primary grains in semi-solid A356 alloy.

Abstract: Influence of weld lines is important to the mechanical properties of the modified polypropylene products. Orthogonal experiments are adopted to confirm injection process parameters for such mechanical properties as impact resistance and tensibility of the modified polypropylene injection-molded parts in weld lines. The factors which affect the mechanical properties at welding joints product vary, and how to select rational parameters is a difficult problem for production. The mechanical strength can be increased through higher temperature, lower injecting pressure, higher velocity of filling, higher packing pressure and longer packing time. The specifications of cross section in weld lines of the products are analyzed to illustrate the theory of fracture. In order to increase mechanical strength of the sample, the length of hot weld lines should be increased and the length of cold welding joints should be decreased through adjusting the process parameter.

Abstract: Deep Cryogenic treatment (DCT) is a one time permanent process, carried out in such a way that the material is slowly cooled down to the cryogenic temperature, after which it is held at that temperature for a specified period of time and is heated back to room temperature at slow rate followed by low temperature tempering. In this study, the orthogonal experiment method was used to study the DCT process of YT30 cemented carbide inserts. The primary relation of the different factors of DCT was analyzed. TH300 sclerometer was used to measure the hardness of inserts. The microscopes were used to observe the wearing profiles of inserts and microstructures before and after DCT. The orthogonal experiment results show that the effect of soaking temperature on the properties of inserts is the first factor, the soaking time is second one, the cooling rate is third one, and the last one is the tempering temperature. DCT improves the multi-type martensite transformation of Co. Therefore DCT increases hardness and enhance wear resistance of the cemented carbide inserts.