Applied Mechanics and Materials Vol. 697

Abstract: The as-cast structure of grate bar used in sintering trolley is primarily comprised of austenite and eutectic (eutectic austenite and eutectic carbide). The austenite is dendrite, while the carbide is reticular and chrysanthemum-like. The grate bars were quenched and tempered under various temperature (one set of samples: quenching (975~1050°C); the other: quenching (1000°C) + tempering (240~600°C)). With rise in quenching temperature, the content of martensite increases and gradually stabilizes, and the hardness increases and then decreases (the maximum is 61.5HRC). For the tempered simple, the strip-like carbides gradually become smaller, shorter and homogenized; the resistance to temper softening is high and the maximum hardness is 58HRC; the wear resistance gradually decreases and is lower than that of as-cast one when the temperature is higher than 480°C. The heat treatment process to improve the service properties of grate bars is: quenching (1000°C, 2.5h, and air-cooling) + tempering (300~420°C, 2.5h, and air-cooling).

Abstract: Owing to the excellent mechanical properties and formability of carbon fiber reinforced thermoplastic composites, this composite has been applied in car industry. The static and dynamic mechanical properties of the composites are investigated under strain-rate from 0.001/s to 50/s. The experimental results show that the elastic model and tensile strength increase with the increase of strain rate, and show that the composite has remarkable rate-hardening effect. A constitute model that including rate-dependent effect is applied to present the strain-stress curve of the composite. The constitute model provides accurate constitute function for finite element analysis of the composite.. The microstructure of the composite is also investigated with scanning electric microscope, and the failure modes are discussed. The investigation provides the basis for engineering application of the composite.

Abstract: BMH is a new type of inorganic antibacterial agent. However, there is few study about BMH application in plastic film. So, in this study, BMH/PE films prepared by rolled was investigated in antimicrobial, mechanical and optical properties with different BMH contents. The results showed that the antibacterial properties increased with the BMH content, and the antibacterial films had strong antibacterial function when the adding amount of BMH was equal or greater than 2%. The mechanical properties firstly increased with the BMH content and then rapidly decreased. The optical properties decreased with BMH content. Taking all properties of the film into account in the study, the antimicrobial film contained 1% BMH was best.

Abstract: The loading sequence effect and life prediction of carbon fiber-reinforced polymer (CFRP) composite materials were experimentally investigated in this paper. All fatigue tests of block loading under four stress ratios R (including 0.1, 0.5, 10 and –1) were carried out on the servo-hydraulic Shimadzu testing machine. The fatigue damage index derived from the linear Palmgren–Miner rule was as reference to evaluate the damage degree. The life prediction model based on residual strength theory was proposed. The experimental results showed that the effect of loading sequence on the fatigue damage was obvious. The relation between the parameter of the proposed model and the stress ratio was studied depending to different failure mode. At last, the contrast of prediction and experimental data indicated that the proposed model had enough accuracy to predict fatigue life of block loading for composite materials.

Abstract: In the oxalate system, some factors of pH values, reactant concentration, feeding method and reaction temperature affecting the grain size and morphology of the precursor of Sm2Fe17 alloy by co-precipitation were investigated. By means of comprehensive experimental and XRD and SEM analysis, the optimum conditions for preparing the precursor of Sm2Fe17 alloy by co-precipitation were obtained and it laid a sound foundation for the subsequent preparation of high-performance magnetic material.

Abstract: In this paper, thermodynamic calculations and reaction process for the production of metal Sm by metal thermal reduction method were analyzed. Two main factors effecting reducing yield were determined, namely: heating system and briquetting. By changing the conditions of heating system and briquetting, the direct yield of metal Sm increased to over 95%.

Abstract: effects of slurry fused Ni60 interlayer on bond strength of cermet coating to GH202 substrate were studied. A compact NiCrBSi interlayer was prepared by slurry fused method and the NiCr-HfB2 cermet coating was fabricated on the interlayer. Surface morphology of the NiCrBSi interlayer and NiCr-HfB2 cermet coating and cross-sectional morphology of samples with the NiCrBSi interlayer were examined by means of SEM. The bond strength of the NiCr-HfB2 cermet coating to GH202 substrate with and without the NiCrBSi interlayer was measured by pulling apart tests. And thermal shock resistance of the cermet coating with and without the intermediate layer was measured. The results show that the NiCrBSi interlayer effectively enhance the bond strength of the NiCr-HfB2 cermet coating to GH202 substrate and the thermal shock resistance of the cermet coating .

Abstract: Woven composites have been increasingly employed in engineering applications. For effective use of woven composites in engineering applications, it is essential to fully understand the mechanical behavior. In the present study, both tensile and compressive behavior of a carbon/glass hybrid woven composite manufactured by vacuum infusion process was experimentally investigated under in-plane quasi-static loading. The experiments were performed at both the axial and off-axial directions. The results indicated that the in-plane mechanical performance of the studied composite was highly directional dependent and tension/compression asymmetric.

Abstract: Silver nanorod array electrodes were prepared by a facile method. The characters of silver nanorod arrays were tested by SEM and XRD. The electrochemical activity of this electrode was tested in the 0.1 mol/L NaClO₄ aqueous solution using chloropropanol as analyte by electrochemical methods. The results of cyclic voltammetry show that silver nanorod array electrodes are good detector for low concentration chloropropanol in aqueous media and display a distinct reduction peak. It is more sensitivity than the bulk Ag electrode. Cyclic voltammetry and Warburg impedance measurements show that the action process between electrode and chloropropanol was controlled by the diffusion and the reaction is totally irreversible. In short, silver nanorod array electrodes show great potential in the determination of trace chloropropanol.

Abstract: The reliability of watercraft depends to a large extent on the reliability of main propulsion plant. It should be distinguished on the base of mission variation charged by watercraft during study of main propulsion plant’s reliability. The mission reliability under rated and economical speed is studied via one main propulsion plant as subject in this paper, while the influence performance degradation of main propulsion plant on its mission reliability mostly studied. Relative curve between mission reliability and working time has been found. The results show that, reliability model in view of performance degradation has good expansibility, approach more to actual malfunction of main propulsion plant, as well as evaluates performance of main propulsion plant well and truly. The results could be guidance for user to establish maintenance schedule in order to improve the mission reliability of main propulsion plant.