节点文献

SiC颗粒增粘铝硅合金泡沫材料的制备工艺及组织特征研究

Study on the Preparation and Characteristics of Organizations of Al-Si Alloy Foam Which Viscosity Increased by SiC Particles

【作者】 张雷

【导师】 刘昌明;

【作者基本信息】 重庆大学 , 材料学, 2008, 硕士

【摘要】 本研究的目的是制定一种熔体铸造法制备SiC颗粒增粘泡沫铝材料的工艺路线及其中各环节的合理的工艺参数,并且得到一种孔隙均匀,孔径大小合适的新型的SiC颗粒增强泡沫铝材料。本文首先比较了传统泡沫铝制备工艺,即用纯铝或合金制备泡沫铝材料和本研究采用的SiC颗粒增粘泡沫铝的不同原理及工艺路线,通过比较得到本研究的工艺路线省去了增粘过程,操作简单易行。随后对发泡剂的分解热力学、分解动力学进行了较为详细的资料分析,得出TiH2在350℃至420℃时开始分解,大量的氢气释放是在420℃以上,在达到钛熔点(1668℃)时结束。温度在600-700℃以下时只有60-75%氢气放出,剩下的气体继续稳定地与金属结合,直到发泡停止。接着分析了熔体铸造法的发泡原理,并对气泡的生成、长大及合并进行了分析,使本研究有了较深刻的理论基础。根据理论分析及前人的经验,确定发泡剂的预处理工艺为400℃下加热24小时,随后500℃下加热1小时,发泡处理时,加入发泡剂之后的搅拌速度为1000r/min,搅拌时间为1分钟左右;为了确定合理的加粉温度,制定了四种工艺,分别为加粉温度为610℃、640℃、660℃、670℃,分别进行试验,通过比较得出,加粉温度为640℃时可以得到较为理想的泡沫材料铸锭。随后分析了未发泡层和发泡不完全区域形成的原因。将制备好的泡沫材料铸锭在轴向不同高度上沿径向锯成圆片状,分别分析每块片状试样上的平均孔径及孔隙率。首先将每块试样沿径向分成三个区域,分别计算每块区域的平均孔径及孔隙率。根据每个区域上的测得的数据,做出片状试样径向方向上及轴向方向上的平均孔径及孔隙率曲线,由各个曲线可知,每块试样的平均孔径及孔隙率沿径向方向增大;试样的平均孔径和孔隙率在轴向方向随高度增加而减小。研究表明:用TiH2做发泡剂,ZL104合金与铝基复合材料做发泡基体可制备一种新型的SiC颗粒增强泡沫铝基复合材料,该工艺操作简单,不需要特殊工艺设备,不需要专门的增粘工艺,具有很好的发展前景。研究同时表明:泡沫材料铸锭平均孔径和孔隙率都由式样中心向式样边缘逐渐增大,另外,随着高度的增加,材料的平均孔径及孔隙率都随之减小,中心区域孔径和孔隙率减小百分率分别为35.7%、42.4%;距式样中心20mm区域孔径和孔隙率较小百分率依次为28.2%、36.5%;距式样中心40mm区域孔径和孔隙率减小的百分率依次为26.3%、33.1%。

【Abstract】 The purpose of this study was to develop the process route and its various elements of reasonable parameters that aluminum foam which viscosity increased by SiC particles can be prepared by melt casting method. And get new aluminum foam with uniform porosity, suitable pore size.This paper compares the different process routes and theory between traditional preparation of aluminum foam, which uses aluminum or alloy of aluminum and this preparation that uses Sic particulate to increase the viscosity of the melt, through comparisons ,we can see that the process route of this study can save the process of Increasing viscosity and can be operated easily. Then the decomposition thermodynamics and kinetics of the blowing agent are analyzed more detailed.TiH2 begins to decompose in the 350℃to 420℃, a large number of hydrogen release in more than 420℃, and the release finishes till the melting point of titanium (1668℃). The hydrogen release only 60-75% under 600-700℃and the remaining gases continue to be steady with the metal-binding until the foam stop. Then the foam theory of the melt casting method is analyzed, the bubble formation, growth and merger are also analyzed. This study has a profound theoretical basis.According to the theoretical analysis and previous experience, the pretreatment process for the blowing agent is to be heated in 400℃for 24 hours, and then 500℃for one hour. The stirring speed when blowing agent is added is 1000r/min; stirring time is about one minute. In order to determine a reasonable temperature for adding powder, four technologies were developed. They are technologies that the powder is added in the temperature of 610℃, 640℃, 660℃, and 670℃. By comparison, in the technology that the powder is added in the temperature of 640℃, we can get more ideal foam. Then the reason why Not foam layer and incomplete foam layer were formed.The prepared foam is sawn into round pieces along radial, Analysis the average pore size and porosity of each sample respectively. Then each of the samples was divided into three regions, the average pore size and porosity of every region was analyzed too. According to the measured data of every region, the curves about the average pore size and porosity of axial and radial directions were made. By the various curves, we can see that the average pore diameter and the porosity of each sample increased along the radial direction; the average pore diameter and the porosity in the axial direction decreases with the height increases.The results show that: a new type of foam can be prepared by using TiH2 as foaming agent and ZL104 alloy and aluminum matrix composite materials as foam matrix. The process is simple, do not require special processing equipment, and do not require specialized process of increasing viscosity. It has good prospects for development.The study also show that: the average diameter and porosity of the foam ingot is gradually increasing from the centre to the edge of the pattern. In addition, with the increase of the high degree, the average diameter and porosity of the foam ingot is gradually decreasing. The decreasing percentage of the average diameter and porosity of the center area are 5.7%、42.4% respectively, and that of the area 20mm far from the center are 28.2%、36.5%, that of the area 40mm far from the center are 26.3%、33.1%,

  • 【网络出版投稿人】 重庆大学
  • 【网络出版年期】2009年 06期
节点文献中: 

本文链接的文献网络图示:

本文的引文网络