| In the preparation of superhard abrasive,the phenolic resin binder has many advantages as following:its curing temperature is very low,its production cycle is shorter than other binders and its production equipment is simple.In addition,the sources of raw materials is wide and the cost is lower than others,and avail to industrial production.Therefore,its application is the most widely.But the phenolic resin itself has some drawbacks:the hydroxyl and methylene structure of phenolic is sasily oxidized,so its heat resistance and resistance to oxidation are affected.Cured phenolic resin is very brittle for aromatic nuclear only connected to methylene.So research to heat resistant of phenolic resin is a focus at home and abroad.In this paper,phenolic resin is modified by boric acid and N-(4-hydroxyphenyl)maleimide(N-HPM),the heat resistance modifed phenolic resin is improved to a certain extent,and its mechanical properties is not reduced.The following aspects was included research work:(1)N-(4-hydroxyphenyl)maleimide Preparation and Characterization;(2)The heat resistant phenolic resin is modified by boric acid or N-HPM respectively,or by both of them at the same time,and test their various performace of modified phenolic resin and determine the best comprehensive properties of modified phenolic resin according to analyzing the test results;(3)Applicate modified phenolic resin of the best comprehensive performance to the superhard abrasive,and further test the main performance of abrasive.Experimental results show:(1)In the synthesis of N-HPM,the optimal technological contions:the synthesis process is one-step method,the catalyst is p-toluenesulfonic acid,and the dosage(mass fraction)is 15%,mole ratio of MA:4-AP is 1.1:1.(2)In the synthesis of modified phenolic resin by boric acid,the heat resistance of best modified phenolic resin with boric acid is PBF with 8%(mass fraction)boric acid content,10%weithlessness temperature is come to 420 ℃,it increase 60℃ than PF;and the flexural strength and impact resistance strength increased by 40.1%and 32.3%than PF.(3)In the synthesis of modified phenolic resin by N-HPM,the heat resistance of best modified phenolic resin with N-HPM is PMF with 6%(mass fraction)N-HPM content,10%weithlessness temperature is come to 456 ℃,it increase 96℃ than PF;and the flexural strength and impact resistance strength increased by 48.7%and 36.5%than PF.(4)In the synthesis of modified phenolic resin by boric acid and N-HPM at the same time,the heat resistance of best modified phenolic resin with boric acid and N-HPM is PMF with 2%boric acid and 6%(mass fraction)N-HPM content,10%weithlessness temperature is come to 490℃,it increase 130℃ than PF;and the flexural strength and impact resistance strength increased by 43%and 40.6%than PF.(5)applicate the best comprehensive properties of modified phenolic resin to superhard abrasive as binder,the main performances of superhard abrasive are tested,the results show:the hardness of modified resin abrasive increased by 42.3%than ordinary PF,the rotation strength increased by 27.3%,the wear rate decreased by 55.3%.The experimental results received from this article has an important theoretical foundation and a good application prospect to further research and develop resin superhard abrasive. |
