Key Engineering Materials Vol. 499

Abstract: This paper proposes a method of determining the constitutive equation parameters of a Japanese type of alloy steel (SCM440H) for Finite Element Analysis (FEA) of orthogonal cutting, involving pressure bar experiments, orthogonal metal cutting experiments and FEA inverse identification. First, Split Hopkinson Pressure Bar (SHPB) experiments combined with Quasi-Static pressure tests were conducted, and after analyzing and processing the experimental data, one set of original constitutive constants was obtained; in the mean time, orthogonal cutting experiments were also performed to collect the cutting force data. Then the original constants were put into FEA software to simulate the cutting process. But comparison between the orthogonal cutting experimental and the simulation results revealed the inadequacy for the constants to predict cutting forces. To address this problem, an inverse identification method was employed to optimize the constants iteratively. And after a certain number of iterations, the ideal parameters for FEA of the orthogonal cutting process were finally determined.

Abstract: Using high-speed oil-filled spinning and multi-pass drawing composite machining methods, a micro straight groove of copper tube(MSGCT) with an outer diameter about 3 mm~6 mm was obtained, and the forming mechanism of micro straight grooves was investigated. The key factors of process parameters influence the drawing were analyzed. The experimental results show that the values of drawing elongation increases with reduction and die angle increasing. However, drawing elongation increases firstly and then becomes smooth with drawing speed increasing. Stable-quality MSGCT can be achieved by controlling the drawing process parameters and the configurations of micro straight grooves were observed by scanning electron microscope(SEM). In addition, the high-speed oil-filled spinning and multi-pass drawing composite manufacturing can further improve the capillary force of the micro straight grooves of copper heat pipe.

Abstract: Recently, researches of composite coatings deposited on the aluminum substrate have been increasing. The Ni-P/nano-diamond composite coating deposited by means of direct electroless deposition on pure aluminum substrate was investigated. The effects of thermal treatment on the surface morphology, microstructure, micro-hardness, and adhesion and elements diffusion of composite coating were examined. Results show that the structure transformation of composite coating from amorphous/microcrystalline into crystalline occurs after thermal treatment and that its micro-hardness increases with the heating temperature and its maximal hardness is 1254Hv after being treated at 350°C for 1h. A diffusion layer forms after thermal treatment due to the inter-diffusion of Al, Ni and P elements at the interface, which leads to the improvement of adhesion strength between the coating and the substrate.

Abstract: Pressure-pushing method of evaluation for adhesion strength of high performance coatings material and substrate is presented. This method, based on the pressure-testing device of high performance bond strength test sample patent, is one that the sample is cracking along the interface by putting the static load. According to the sample’s stress boundary conditions, the formula of the adhesion strength is given. The surface coating/substrate interface stress distribution is analyzed by using the finite element method, which provides the theory basis for the correct evaluation of coating/substrate strength. The experiments are conducted on the strength of common coating substrate materials as well. All the results show that pushed method can test the adhesion strength of high performance coatings and substrate, whose data is smaller than the international standard and A STMC633-79. And the experimental data of the pushed method are free from the influence of random factors.

Abstract: The hinge-type turning fashion has been widely adopted in wheel loader. During the process of design, two kinds of parameters, stability and stability coefficient, have been thought out to evaluate a loader’s transverse stability. Majority of cultural documentary adopts the evaluation method of stability currently.In this paper, the opinion that the stability coefficient can be used to evaluate transverse stability is more reasonable and viable, which is proved and analyzed through experiments.It is certificated by theory and practice: Using the stability coefficient to evaluate a loader’s transverse stability is more scientific and exact. It has some significance to direct the design, manufacture and use of the wheel loader.

Abstract: In feed industry, the production efficiency is the main index to judge the performance of pellet mill. The stability of the pelleting process has an important influence on the production efficiency, and the rigidity of the roller bracing structure has a great effect upon the stability of the pelleting process. To improve the rigidity, two extra supporting shafts were usually used in the roller bracing structure system. According to the positions where the supporting shafts locate, the cross-sectional shape and area of the supporting shafts, six different kinds of supporting schemes were designed in this paper. Then the deformation of the roller in different supporting schemes were comparatively analyzed. The analysis results can provide an important reference to improve the stabilization of the pelleting process.

Abstract: This paper provides heat transfer modeling analysis and parameter optimization for wafer system of laser annealing equipment. Heat transfer models are established at axial and radial directions. With the help of programming calculation, the relation between heat flux of radiation and distance of adjacent layers can be analyzed. In order to minimize heat transfer interference on the motor system, optimized parameters are selected. Performance of certain selection is verified by FEA simulation and experiment data.

Abstract: Starting with 22MnB5 boron and magnesium alloy sheet material forming temperature, cooling rate and phase deformation, the impact of cooling rate and temperature change on rebound during hot-stamping as well as the impact of factors such as sheet material thickness on high strength sheet material forming performance. The study shows that the initial conditions, temperature changes during thermal forming and phase deformation are the main factors affecting rebound. When the cooling rate is above the critical cooling rate, rebound increases dramatically. The sheet material thickness has important impact on rebound control and formulating parameters for thermal forming process.

Abstract: Osmium (Os) may be used as new barrier material in copper interconnects of ultra-large scale integration. In this work, chemical mechanical polish experiments were done on Os disk using home-made slurry, the effect of pH value, down force, chelating agents, inhibitor species, the concentration of the inhibitor, H2O2 concentration and SiO2 concentration on material removal rate (MRR) was investigated. The results reveal that MRR is 13.1 nm/min when the slurry contains 1wt.% H2O2, 1wt.% SiO2, 1 wt.% citric acid, 1mM BTA and pH =9 and the down force was 1 psi. The influence of the BTA concentration on the corrosion on the surface of Os was analyzed using electrochemical analysis method; it was found that the maximum value of Ecorr appeared when the BTA concentration was 1.5 mm

Abstract: Al2O3-TiN nanocomposite ceramic tool materials were fabricated by hot-pressing technique and the mechanical properties were measured. Mechanical properties such as room temperature flexural strength, Vickers hardness and fracture toughness were measured through three-point bending test and Vickers indentation. The effects of the content of nano-scale TiN, sintering temperature and holding time on the mechanical properties were investigated. The results shows that the addition of nano-scale TiN can improve the mechanical properties of alumina ceramics. Both the flexural strength and the fracture toughness first increased then decreased with an increment in the content of nano-scale TiN. Both the Vickers hardness and the fracture toughness increased with an increment in the sintering temperature. The flexural strength increased with an increment in the holding time, while the fracture toughness decreased with an increment in the holding time. The composites with only nano-scale TiN have the highest Vickers hardness for the holding time of 30min, while the hardness of the composites with nano-scale TiN and micro-scale TiN decreased with an increment in the holding time.