Applied Mechanics and Materials Vol. 692

Abstract: The dry sliding friction test of normalized T10 steel against hardened quenched and tempered 20CrMnTi steel under normal load of 60 N and sliding speed of 0.29m/s was carried out on a pin-on-disc tribo-tester. The microstructures in the worn surface layer of T10 steel pin and 20CrMnTi steel disc were analyzed by OM, SEM, and TEM, which were all severely plastically deformed. The ultrafine and even nanoferrite grains (5 nm to 200 nm) were observed in the worn surface layer of T10 steel pin, which was considered to be the result of severely shear deformation.

Abstract: The copolymer of sodium polyacrylic acid and 2-acrylamide-2-methyl propane sulfonic acid (AMPS) was prepared by radical polymerization process, the effect of mass ratio of AA/AMPS on the viscosity of AA-AMPS copolymer were investigated. Results showed that when the mole ratio of AA/AMPS was 3:1, it had the least viscosity. The dispersion stability of synthesized AA-AMPS copolymer for nanozinc oxide was tested.

Abstract: Three anionic sulfonic groups are used as monomers to synthesize sodium polyacrylic copolymers by radical polymerization process. The anionic sulfonic groups are: sodium acrylic sulfonate (SAS), sodium styrene sulfonate (SSS) and 2-acrylamide-2-methyl propane sulfonic acid (AMPS), the redox initiator are ammonium persulfate and sodium bisulfite, the chain transfer agent is sodium bisulfite. The influence of different anionic sulfonic groups on dispersion stability of nanozinc oxide has been discussed.

Abstract: The hypothesis of the flushing fluid that is evenly distributed and flowing on the surface of the wet filtering layer fiber was first introduced in the paper, on which the concept of equivalent diameter of the composite trap was given to build the theoretical model of filtration resistance of wet fiber layer for aerosol particles, therefore the theoretical formula of wet filtration resistance has been derived, making possible the theoretical research on the filtration and purification resistance of wet fiber layer for dust particles. Based on the theoretical analysis, a semi-theoretical and semi-empirical formula that can be applied to the practical use has been eventually obtained by means of the necessary dimensionless correction of the theoretical results through simulation experiments, the formula and the methods of research questions are of guiding significance and conductive to the filtration and purification of wet fiber layer for aerosol particles.

Abstract: Being added by H₃BO₃ as flux, the nanosize strong green phosphor Zn₂SiO₄: Mn²⁺ was prepared by an improved sol-gel method. The structure and the morphology of the samples were examined by XRD, UV-VL spectrophotometer and SEM. The photoluminescence properties were measured by fluorescence spectrometer. Results show that, when the samples were annealed at 850°C for 2 hours, the intensity of emission spectrum of the sample is not strictly followed the monotonically increasing with the increase of Mn²⁺ doping concentration. It appears in a fluctuated tendency with the increase of doping concentration. In the 4% Mn²⁺ doping concentration and annealing temperature 950°C, the most strong green emission spectrum can be obtained. The mechanism of luminescence properties of this kind of material is analyzed.

Abstract: The BN powder with high specific surface area was successfully prepared using an airtight high-temperature reactor with NH₃ as the reaction atmosphere and protective atmosphere. The influences of raw material ratio and reaction temperature on the specific surface area of obtained BN powder were investigated through the analysis on the powder yield, purity and specific surface area. The results shows both of raw material ratio and reaction temperature have influence on the specific surface area of BN powder. And the reaction temperature has more influence. More important, the BN powder with a specific surface area of 279.62m²/g and an average pore diameter of 4.19nm was obtained by the optimum process.

Abstract: Microstructural evolution of AZ61 magnesium alloy was analyzed after ECAE process. This research focused on the effects of deformation temperature and extrusion passes on microstructure of AZ61 magnesium alloy. The results showed that microstructure have not improved significantly at the lower temperature. Grains can be refined greatly at deformation temperature of 370°C. With an increase of extrusion passes, grains tend to be much refined, which is beneficial to obtaining good property.

Abstract: The environmental friendly catalyst, H₄SiW₁₂O₄₀/TiO₂-SiO₂ was prepared by the impregnation method. The synthesis of cyclohexanone glycol ketal was as the probe reaction and investigated the different influences on the catalytic activity of H₄SiW₁₂O₄₀/TiO₂-SiO₂ by the quality of the carrier TiO₂-SiO₂ ratio, load of heteropoly acid, catalyst preparation conditions of the activation time and the calcination temperature, etc. The results showed the best condition for the preparation of the catalyst is the mass ratio of TiO₂ and SiO₂ is 1: 5, the load ratio of H₄SiW₁₂O₄₀ is 10 %, calcination temperature is 300 oC and the roasting time is 3.0 h. Under the condition of the molar ratio of aldehydes (ketones) and glycol (1,2-propanediol) is 1: 1.6, the mass percent of the catalyst is 1.4 %, and the reaction time of 70 min, the yields of eight kinds acetal (ketal) are 71.6 %~ 90.5 %.

Abstract: A new environmental friendly catalyst, H₄SiW₆Mo₆O₄₀/TiO₂-SiO₂ was prepared by impregnation method, the synthesis of cyclohexanone 1,2-propanediol ketal was the probe reaction to optimize the synthetic condition of catalyst. The reactive condition of catalyst was optimized by orthogonal test method. The optimum conditions are n (TiO₂): n (SiO₂)= 3: 1, 20 % mass ratio of m (H₄SiW₆Mo₆O₄₀): m (TiO₂-SiO₂), the calcined time is 3 h and 300 °C of activated temperature. Using H₄SiW₆Mo₆O₄₀/TiO₂-SiO₂ as catalyst, adipic acid was synthesized from the oxidation of cyclohexanone by 30 % H₂O₂. Influences of dosage of H₄SiW₆Mo₆O₄₀/TiO₂-SiO₂, reaction temperature, volume of hydrogen peroxide and reaction time were discussed. Experimental results showed that H₄SiW₆Mo₆O₄₀/TiO₂-SiO₂ is a good catalyst for synthesis of adipic acid. When n (cyclohexene): n (H₂O₂): n (H₄SiW₆Mo₆O₄₀/TiO₂-SiO₂)= 100: 979: 0.04, reaction temperature is 130 °C and reaction time is 5 h, under the optimum conditions, the yield of adipic acid is 45.9 %.

Abstract: A craft of carbothermic reduction-magnetic separation process is investigated for the recovery of iron from cyanide residues, a hazardous industrial wastes when produce gold with cyanide leaching method. The cyanide residues, containing 30.12% Fe was conducted for the craft. The results demonstrated that iron concentrate with 60.25% Fe and 79.85% of iron recovery was obtained under the optimal conditions (a reduction temperature of 950°C, a reduction duration of 60 min, a pulverized coal dosage of 10% and a potassium carbonate dosage of 4%).This craft can be used to utilize cyanide residues and produce qualified concentrate as iron-bearing feed for steel industry, which will help to solve the pollution of cyanide residues and extend raw material sourcing for Chinese steel industry.