Advanced Materials Research Vols. 189-193

Abstract: Based on the phenomena the grain boundaries first-order phase transition in range 0.55 – 0.86 of metal melting point with formation of two-dimensional liquid was elaborated the technology of coatings by synthesis of nitrides using of gaseous nitrogen. It was studied the steel elements for forcing-lift of diesel after nitriding. The creation of a concentration gradient of summary nitrogen (from 1.9 up to 0.5 % at) in a layer of alloy up to 3 mm from a surface results in forming graded coatings with step changes of properties. The mechanical behavior of new tools with high surface resistance to wear are defined of the combination of high hardness (800-1000 Hv[GPa]) of surface coatings (enriched of a nanosize nitrides) with high impact toughness of transitional to matrix layer. The tools life times improved more then 1.5 – 2.5 times.

Abstract: The process calculation of producing stainless steel crude melts by smelting reduction in a 150 t converter is carried out for the first time by use of the empirical data and calculation method of refining plain carbon steel in a converter, according to the blowing conditions of 185 t smelting reduction converter of No.4 steelmaking shop in Chiba Works of JFE Steel. Using the self-programming procedure for the processing calculation, the proper coke quantity and a complete set of calculation data for the process of smelting reduction in a converter are obtained, including the batch calculation, the material balance and heat balance calculations. The calculation results show that the increase of PCR can decrease the quantity of coke and actual oxygen consumption considerably, and improve the thermal efficiency of smelting reduction converter. For producing 18 wt% Cr stainless steel crude melts, comparing with the process of electric arc furnace, the process of smelting reduction in a converter can reduce the production cost greatly. The use of the recycled metal containing chromium can shorten blowing time and improve the yield of chromium.

Abstract: Reaction process of BOF steelmaking is a very complex physical chemistry process which is very difficult to describe linearity. The traditional static model has poor accuracy, and the target hit rate is low. Based on the analysis of the major influential factors, the influential factors of converter smelting on the endpoint control of carbon content are fixed in this paper. A prediction model of end-point carbon content for BOF is established based on Levenberg-Marquardt (LM) algorithm of BP neural network. The simulated results show that the hitting rates of end-point carbon content reached 80% when accuracy of target error is ±0.025%.

Abstract: Hydraulic support is an important equipment of coal mine production. Its design and manufacture level affects the safe production and economic benefits of coal mine directly. This paper took ZT6500/19.5/34 hydraulic support as an example. First, three dimensions solid models of the type simplified hydraulic support prototype and its 1:5 model were constructed by three dimensions construction model software SolidWorks. Then, three dimensions solid models were led in ANSYS software. Finally, the strength test of the type hydraulic support prototype and its 1:5 model were proceeded under base torsion working condition by ANSYS software. The relevant total displacement distribution rule and equivalent stress distribution rule of the type simplified hydraulic support prototype and its 1:5 model were found. The proportion relation of total displacement and equivalent stress between the type simplified hydraulic support prototype and its 1:5 model were confirmed. This provides an effective way of design and research hydraulic support.

Abstract: Hydraulic support is an important equipment of mechanization caving coal in modernization coal mine. Hydraulic support strength test is a key link in hydraulic support design. Based on the similarity theory, the displacement, stress and strain information of test measured from hydraulic support model test can be popularized to hydraulic support prototype. This has an important significance on successful pass in prototype hydraulic support strength test and quicker and better designing eligible hydraulic support. The construction of load equipment and hydraulic control system of hydraulic support model test provides a practical and convenient research way of hydraulic support model test.

Abstract: SiCp/Z101 composites substrate can be successfully fabricated by pressureless infiltration of ZL101 alloy liquid into porous SiCp preform, the relative density are nearly up to 99%. This is mainly because that generated SiO₂ phase on the surface after sintering of SiCp not only has joint function to the porous of SiC perform, but also obtains two-phase wetting between SiC and Al matrix through the interface reaction, resulting in promoting spontaneous infiltration. SiC preforms have almost no change of shapes and sizes after infiltration of Al liquid and can achieve near-net-shape of the composites for substrate. Volume fraction of SiC can be effectively improved by using binary mixture particles with the diameter ratio of 11:1, through which the properties of substrate can be controlled effctively. By the addition of SiCp, strength of the composites is improved remarkably, and its elastic modulus increases correspondingly about one time, the increase of SiC volume fraction can markedly reduce coefficient of thermal expansion (CTE) of composites , but meanwhile decrease thermal conductivity(TC) of composites, and its TC (at 50 °C ranges from 120.7 W/(m•k) to 99.4 W/(m•k) and its mean linear CTE (25°C to 50°C ) ranges from 9.47×10⁻⁶ k^-1 to 7.05×10⁻⁶ k^-1 as volume fraction of SiC ranges from 38% to 68%.

Abstract: The glass composition CaO-Al₂O₃-B₂O₃-SiO₂ as an alternative glass composition, and commercial α-Al₂O₃ as a ceramic material was used. The structure of the glass was analyzed by infrared spectra; the glass-ceramics thermal expansion coefficient was measured by dilatometer, the phase separation of the sample was investigated by scanning electron microscope and the component of phase was analyzed by X-ray. The results show that [BO₃] increases and [BO₄] decreases in the glass structure with the increasing of B₂O₃ content added into CaO-Al₂O₃-B₂O₃-SiO₂ glass. The relative density and dielectric constant (εr) are considerably decreased with the addition of amount of B₂O₃. Excellent microwave dielectric properties of 1MHz, εr = 8.0 and tanδ=0.003 are obtained by adding 10 wt% B₂O₃ to glass-ceramic and sintering at 875°Cfor 30 min.

Abstract: The microstructural evolutions of 7055 aluminum alloy after single and two-step homogenization with or without applying 12T high magnetic field were investigated. The as-cast microstructures of 7055 alloy consist of α+AlZnMgCu eutectics, Al7Cu2Fe phase and AlTiCuFe phase. During homogenization, coarse α+AlZnMgCu eutectics located at interdendritic region become smaller, discontinuous and spheroidized, some of them transform into Al2CuMg (S) having a higher melting point. High magnetic field significantly accelerates the dissolution of α+AlZnMgCu eutectics and S phase. The least amount of α+AlZnMgCu eutectics and S phase is obtained when the alloy homogenized at 4650C/10h+4850C/8h under 12T high magnetic field.

Abstract: The effects of DC and AC magnetic field on the phase composition, morphology and distribution of the ternary Al-Fe-Si alloy were investigated. The solidification structures of the alloy solidified with and without the application of magnetic fields were confirmed by DSC and structural measurements. The results showed that, in this Al-Fe-Si alloy the fine needle-like Al3Fe phase dominated the microstructure at the grain boundaries with the minor amount of Chinese script-like α-AlFeSi. Distribution of Al₃Fe phase was almost homogeneous in the volume of the sample when alloy was solidified in the conventional condition. When the DC magnetic field was imposed, distribution of Al₃Fe phase was more homogeneous. However, the Al₃Fe and α-AlFeSi phases were accumulated towards the center of the sample with the application of the AC magnetic field. This is due to the difference of Lorentz force between Al matrix and iron-containing intermetallics. Furthermore, the amount of Chinese script-like α-AlFeSi was increased remarkably under AC magnetic field.