Applied Mechanics and Materials Vols. 80-81

Abstract: It had been studied that thermal deformation properties of AerMet100 steel (AMT100) by thermal simulation on Gleeble 3500 Simulator, which the ranges of temperature and strain rates were 900～1100°C and 0.01～10/s. According the experiment data, the parameters of thermal deformation was calculated, in which the activation energy is 261.2KJ/mol. The strain-rate sensitivity coefficient is m=0.0998, and temperature sensitivity coefficient is s=7912. The relationship among peak stress and deformation temperature and strain rate was established. And the ranges of temperature and strain rates were 900～1100°C and 0.01～10/s, and the relative errors of calculation results by the stress-strain model were less than 11.3%.

Abstract: A set of modified marine corrosion simulation test device was designed in this study according to the characteristics of the natural marine environment, in order to study the corrosion behavior of steel materials. The natural corrosive marine environment could be simulated indoors by the device, which had advantages such as sea water self-circulation, stable wave, multi-level adjustable amplitude and frequency and so on. Components modeling, overall assembly and motion simulation were carried out by UG program, and the interference among the various components, limit position of movement and motion parameters were analyzed, effectively avoiding the problems that may arise during processing, manufacturing and assembly process.

Abstract: Different from traditional engine test, an optical constant volume chamber simulated HTHP ambient condition was employed by using biodiesel-diesel-butanol blends. With high-speed camera and synchronized copper vapor laser, recorded fuel spray and combustion process, measured liquid jet penetration length and heat release rate under variable ambient temperature and fuel composition conditions. With ambient temperature increasing, burn process converted from premixed combustion to diffusion combustion, and the micro-explosion became weak and disappeared. It was concluded that micro-explosion could occur under particular initial ambient temperature and specific blend ratio conditions for the biodiesel-diesel-butanol fuel, that will distinctly enhance fuel evaporation and premixed combustion process.

Abstract: This paper is about the study of the KF301/WS₂ composite lubrication wear-resisting coatings prepared by supersonic plasma spraying. Basing on the research of the tribological characteristics, it has been discussed the self-lubricity and the failure mechanism showed by composite lubrication coatings under high-temperature conditions. Research shows that the wear rate of the coatings increased with the increase of the temperature. At 300°C, the wear rate is 1.02×10^-4mg/m; At 750°C, the wear rate is 2.61×10^-4 mg/m. With the increase of temperature, friction coefficient of the coatings shows gradually increasing. When the temperature falls below 600°C, friction coefficient keeps around 0.08; At 750°C, the friction coefficient is 0.12. Temperature has great effect on the friction and wear properties of the self-lubricating wear-resisting coatings, mainly manifests in two aspects: first, with the increase of the temperature, under the common influence of thermal stress and frictional contact stress, it promotes the WS₂ solid lubricant film cracking, breakage, shedding process, and lubrication and abrasive resistance reduces; on the other hand, the WS₂ occurs chemical reaction under high temperature, generating lubricity phase of NiWO₄, CrS, and lubricity phases are well supplied, lubricating film has an effect of continuous lubrication on the rubbing surface, So the coating shows low-friction, and it also represents that the KF-301/ WS₂ self-lubricating composite coating has good lubrication and abrasive resistance under high temperature．

Abstract: This paper is about the study of the KF301/WS₂ composite lubricating wear-resisting coatings prepared by supersonic plasma spraying. Basing on the research of the tribological characteristics, it has been discussed that the thermal stress of lubricating wear-resisting coating prepared by supersonic plasma spraying in the high-heat tribological process. Research shows that the wear rate of the coating increases with the increase of the temperature. At 300°C, the wear rate is 1.02×10^-4mg/m; At 750°C, the wear rate is 2.61×10^-4 mg/m. With the increase of temperature, friction coefficient of the coatings shows gradually increasing. When the temperature falls below 600°C, friction coefficient keeps around 0.08; At 750°C, the friction coefficient is 0.12. The thermal stress σ_1max mainly is controlled by temperature, with the increase of temperature, the warping phenomena of solid lubricant film and the combined effects of heat stress and friction contact stress, which causes the insecure combination of the lubricant film and substrate, lubricant film’s warp, break, local direct contact between the metals, which is one of reasons to lead to decrease of the tribological properties of self-lubricating composite coating.

Abstract: Using the surface self-nanocrystalline technology can produce dense nano layer without the defects such as pores. The surface self-nanocrystalline technology can improve the micro hardness, abrasive resistance, fatigue durability, corrosion resistance and other combination properties. It is with wide application prospect in the industrial area. In this article, the application investigation of the surface self-nanocrystalline technology such as the surface mechanical polishing method, ultrasonic impacting method, ultra sound peening ect. improving the prehensive properties of the materials are summed up. And the study work of the surface self-nanocrystalline technology in the future is prospected here.

Abstract: In this study, biosorption of C. I. Acid Red 18 from aqueous solution was investigated by using acid treated biomass of Penicilium sp. in a batch system. The effects of initial pH, contact time, initial dye concentration and temperature on dye biosorption were investigated. Optimum pH for efficient dye biosorption was found to be 3.0 for acid treated biomass. The bosorption capacity was increased with the increasing temperature in studied temperature range. The Langmuir and Freundlich isotherm models were applied to experimental equilibrium data and the Langmuir model better described the equilibrium dye uptake than the Freundlich model. Thermodynamic studies revealed that the biosorption process was successful, spontaneous and endothermic in nature.

Abstract: Nanodiamond/Ni and Ni coatings were fabricated via brush plating. Nanocrystalline structure of the composite coating was investigated by SEM and XRD. The results showed that the composite coatings are nanocrystalline structure. The hardness of the nanodiamond/Ni composite coating is higher greatly than that of Ni coating. At same time, the reasons of formation nanocrystalline were discussed, which include the nucleation rate with the increase of a high over-potential, the reciprocating motion between brush and work piece, the heterogeneous nucleation of nanodiamond. The nanodiamonds as second phases make grain finer. The nanodiamonds of core-shell structure play the important role in wear resistance and antifriction. So the wear resistance of the composite coatings is significantly higher than nickel coating’s.

Abstract: Lead zirconate titanate thick films with thickness of 1-3μm have been prepared by a sol-gel process. Influence of film thickness on microstructures and dielectric properties of the films were investigated. The film thickness dependent of microstructures was studied by XRD and Raman spectrum. The PZT films were dense and possessed preferential crystal orientation. Ferroelectricity and dielectric properties were confirmed by P–E hysteresis loops and C-E measurements. The dielectric constant and dielectric loss of the film with thickness of 3.045μm were 2000 and 0.055, respectively. The decrease of the coercive field and the increase of the remanent polarization with the increase in thickness were observed. As film thickness was increasing, PZT thick films had higher (110)-preferred growth orientation and excellent dielectric and ferroelectric properties.

Abstract: In order to measure the pressure in the ultra-low temperature condition, the structure of ultra-low temperature piezoresistive pressure sensor is designed. Polysilicon nanometer thin film is used as a varistor according to its temperature and piezoresistive characteristics. The effect of the dimensions of silicon elastic membrane for the sensor sensitivity and the strain dimensions of the elastic membrane are analyzed, then layout position of resistances is arranged. The package structure of pressure sensor is designed. Meanwhile, a low-temperature sensor is designed to compensate the temperature influence to the pressure sensor.