Mechanical vibration was applied to the solidification of a lost foam cast(LFC) 356 aluminum alloy.Effects of mechanical vibration,with different peak acceleration,on the size and morphology of α-Al phase,and also on...Mechanical vibration was applied to the solidification of a lost foam cast(LFC) 356 aluminum alloy.Effects of mechanical vibration,with different peak acceleration,on the size and morphology of α-Al phase,and also on the mechanical properties of the castings were studied.Results indicated that α-Al dendrites gradually grow into equiaxed grains as the peak acceleration of vibration is increased.When the peak acceleration is between about 1 to 4 g,α-Al phase distribution is uniform and is refined obviously.α-Al dendrites are reduced and the mechanical properties of the castings are improved significantly when compared to those of the castings that are produced without vibration.However,when the peak acceleration is higher than 4 g,strong vibration will lead to defects formation,such as sand adhesion,while the amount and size of pores will be increased.And due to the turbulent flow that caused by strong vibration,the chance of forming large pores in the matrix has been increased significantly.The increase in defects will result in the deterioration of mechanical properties.展开更多
The sodium silicate bonded sand hardened by microwave heating has many advantages,such as low sodium silicate adding quantity,fast hardening speed,high room temperature strength,good collapsibility and certain surface...The sodium silicate bonded sand hardened by microwave heating has many advantages,such as low sodium silicate adding quantity,fast hardening speed,high room temperature strength,good collapsibility and certain surface stability.However,it has big moisture absorbability in the air,which would lead to the compression strength and the surface stability of the sand molds being sharply reduced.In this study,the moisture absorbability of the sodium silicate bonded sand hardened by microwave heating in different humidity conditions and the effect factors were investigated.Meanwhile,the reasons for the big moisture absorbability of the sand were analyzed.Some measures to overcome the problems of high moisture absorbability,bad surface stability and sharply reducing strength in the air were discussed.The results of this study establish the foundation of green and clean foundry technology based on the microwave heating hardening sodium silicate sand process.展开更多
基层生态环境监测站对于环境监测实验过程中使用化学品的安全管理措施已不能完全适应现代安全管理的要求。研究基于目前基层生态环境监测站化学品管理现状及存在的问题,结合环境监测实验室的实际情况,分析了引入化学品安全说明书(materi...基层生态环境监测站对于环境监测实验过程中使用化学品的安全管理措施已不能完全适应现代安全管理的要求。研究基于目前基层生态环境监测站化学品管理现状及存在的问题,结合环境监测实验室的实际情况,分析了引入化学品安全说明书(material safety data sheets,MSDS)信息管理体系的架构和目的,探讨了实验室信息管理系统(laboratory information management system,LIMS)与MSDS功能融合意义,提出了实验室化学品管理的一般要求以及建立应对突发事件的应急处置预案,以强化环境监测实验室化学品购买与储存管理、使用管理、人员管理、无害化处置管理,进而规范环境监测实验分析和化学品使用安全管理,确保化学品在基层生态环境监测站的安全使用。展开更多
基金supported by the National High Technology Research and Development Program of China (Grant No.2007AA03Z113)The National Natural Science Foundation of China (Grant No.50775085)
文摘Mechanical vibration was applied to the solidification of a lost foam cast(LFC) 356 aluminum alloy.Effects of mechanical vibration,with different peak acceleration,on the size and morphology of α-Al phase,and also on the mechanical properties of the castings were studied.Results indicated that α-Al dendrites gradually grow into equiaxed grains as the peak acceleration of vibration is increased.When the peak acceleration is between about 1 to 4 g,α-Al phase distribution is uniform and is refined obviously.α-Al dendrites are reduced and the mechanical properties of the castings are improved significantly when compared to those of the castings that are produced without vibration.However,when the peak acceleration is higher than 4 g,strong vibration will lead to defects formation,such as sand adhesion,while the amount and size of pores will be increased.And due to the turbulent flow that caused by strong vibration,the chance of forming large pores in the matrix has been increased significantly.The increase in defects will result in the deterioration of mechanical properties.
基金supported by the National Nature Science Foundation of China under grant No.50575085
文摘The sodium silicate bonded sand hardened by microwave heating has many advantages,such as low sodium silicate adding quantity,fast hardening speed,high room temperature strength,good collapsibility and certain surface stability.However,it has big moisture absorbability in the air,which would lead to the compression strength and the surface stability of the sand molds being sharply reduced.In this study,the moisture absorbability of the sodium silicate bonded sand hardened by microwave heating in different humidity conditions and the effect factors were investigated.Meanwhile,the reasons for the big moisture absorbability of the sand were analyzed.Some measures to overcome the problems of high moisture absorbability,bad surface stability and sharply reducing strength in the air were discussed.The results of this study establish the foundation of green and clean foundry technology based on the microwave heating hardening sodium silicate sand process.
文摘基层生态环境监测站对于环境监测实验过程中使用化学品的安全管理措施已不能完全适应现代安全管理的要求。研究基于目前基层生态环境监测站化学品管理现状及存在的问题,结合环境监测实验室的实际情况,分析了引入化学品安全说明书(material safety data sheets,MSDS)信息管理体系的架构和目的,探讨了实验室信息管理系统(laboratory information management system,LIMS)与MSDS功能融合意义,提出了实验室化学品管理的一般要求以及建立应对突发事件的应急处置预案,以强化环境监测实验室化学品购买与储存管理、使用管理、人员管理、无害化处置管理,进而规范环境监测实验分析和化学品使用安全管理,确保化学品在基层生态环境监测站的安全使用。
