羰基镍粉末悬浮液性能研究

INVESTIGATION OF THE PROPERTIES OF NI SUSPENSIONS

湿法成型在降低粉体团聚、改善素坯显微结构均匀性方面有着明显的优势。本工作采用乙醇为溶剂 ,PVB为分散剂和粘结剂 ,对以固相含量为 55% (质量分数 )的羰基镍粉悬浮液的制备和性能进行了研究。包括 :通过测定悬浮液的黏度和最终沉降体积确定最佳分散剂含量 ;含有粘结剂的悬浮液分两个阶段制备 :第一阶段悬浮液由羰基镍粉、乙醇和 0 2 % (质量分数 )PVB(分散剂 )组成 ,球磨 2 4h ,目的是打开颗粒团聚体和润湿粉料 ;第二阶段主要致力于悬浮液与粘结剂的混合 ,分别加入不同量的PVB ,球磨 2 4h。结果表明 ,分散剂含量为 0 2 %(质量分数 ) (相对于粉体 )时能使羰基镍粉末得到良好的分散。当粘结剂含量少于 6 % (质量分数 )时 ,在涂层坯体过程中容易出现裂纹 ,而粘结剂含量高于 6 %(质量分数 )时 ,悬浮液中含有较多的气泡。含 0 2 % (质量分数 )分散剂 ,6 % (质量分数 )粘结剂时可获得黏度适中 。

The wet forming method has great advantage in reducing the agglomerates and improving the homogeneity of powder compacting materials.The preparation and properties of Ni suspensions was studied.The Ni suspensions consist of 55wt% nickel powder,using ethanol as solvent,and polyvinyl butyral as dispersant and binder.The quantitative optimization was done from measured values of the viscosity and final sedimentation volume fraction of the suspensions with various concentrations of dispersant PVB.The suspensions were prepared in two stages.Firstly,the dispersant was added to the solvent and followed by nickel powder.This slurry was ball milled for 24 hr in order to separate nickel particles and to break up weak agglomerates.Then secondly,the binders were added to above suspensions and the resulting slurry was milled also for 24hr.It is shown that the nickel powders can dispersed well in the suspensions which contains 0.2wt% dispersant PVB.For those with binder content lower than 0.2wt%,cracks were noticed when the green coatings were dried.For those with binder content more than 4wt%,there were many air bubbles in the suspension.The nickel suspension with suitable viscosity and stability can be obtained when 0.2wt% dispersant and 4wt% binder contained.