利用碱渣和金尾矿协同制备多孔陶瓷中孔结构和晶相的影响因素研究

Influence factors of pore structure and crystal phase in preparation of porous ceramics with alkali residue and gold tailings

以双固废(金尾矿和碱渣)制备的保温型泡沫陶瓷为基础,考察了温度、发泡剂、助熔剂、稳泡剂的含量对Ca-Mg-Al-Si体系多孔陶瓷孔结构和晶相的影响,采用Image-Pro Plus 6.0软件对多孔产品的孔径分布进行了统计学分析,讨论了烧结过程中原料基本组成对微观结构的影响。研究发现:升高温度,会破坏硅酸盐聚合度,改变非晶态物质含量,通过影响熔体黏度改变孔结构;发泡剂SiC对孔结构的调节主要通过改变添加量来控制孔内气体压力P_(g),从而调节孔结构;Al对孔结构的影响存在两面性,当Al含量低时(n Al_(2)O_(3)/n_(MO)<1,M=Ca,Mg,K,Na),Al—O配位体为四面体,当Al含量高(_(nAl _(2)O _(3))/n_(MO)>1)时,Al—O配位体为八面体,配位变化会引起黏度的复杂变化;Ca对孔结构的影响分两个阶段,Ca含量低时,主要参与打破硅酸盐网络结构,Ca含量高时,其参与生成少量辉石晶体;Mg通过生成辉石晶体,对孔结构进行调控,但Mg含量过高时,生成的大量针状晶体会对气孔产生过度抑制,导致气孔不能正常发育。

This paper investigated the effect of temperature,foaming agent,fluxing agent and foam stabilizer contents on the pore structure and crystal phase of porous ceramics in Ca-Mg-Al-Si system based on the thermal insulation foam ceramics prepared from two solid wastes(gold tailings and alkali residue).Image-pro Plus 6.0 software was used to analyze the pore size distribution of porous products.The effect of basic composition of raw material on microstructure in sintering process was discussed.It is found that the increase of temperature will destroy the polymerization degree of silicate and change the content of amorphous materials,thus adjusting the viscosity and change the pore structure in turn.The pore structure can be regulated by the foaming agent SiC mainly by changing the adding amounts to control the gas pressure P_(g) in the pore.The effect of Al on the pore structure is two-sided.When the Al content is low(n_(Al_(2)O_(3))/n_(MO)<1,M=Ca,Mg,K,Na),the Al—O ligand is tetrahedral;when the Al content is high(n_(Al_(2)O_(3))/n_(MO)>1),the Al—O ligand is octahedral.The changes in coordination will lead to the complex changes in viscosity.The effect of Ca on the pore structure can be divided into two stages:When the Ca content is low,it mainly participates in breaking the silicate network structure;when the Ca content is high,it participates in forming a small amount of pyroxene crystal.Mg regulates the pore structure through the formation of pyroxene crystals.However,when the Mg content is too high,a large number of needle-like crystals will exert excessive inhibition on the pore,leading to the abnormal development of the pore.