Studies On Modified Phenolic Resin In The Resin Binders Of Superhard Materials

Because the resin bonded diamond grinding wheel with a sharp,abrasion resistance,good processing accuracy and other characteristics,there is a relatively large share in superhard materials market.Determinants of grinding performances of resin grinding wheel are the main performance of diamond,diamond and matrix interfacial adhesion and bond properties,among which the last one has the greatest effect.Phenolic resin is the world's first synthetic resin of discovery and industrialization.As a kind of resin binder,it is easy to get raw materials,has low cost and simple synthesis process,as well as has been widely used in composite materials,coatings,adhesives and other fields.But the structure of common phenolic resin is two phenol with a methylene,which causes too large density of benzene ring,steric hindrance,low degree of freedom in chain rotation.As a result,the impact resistance(toughness)of pure phenolic resin is poor;at the same time,due to easy oxidation of phenolic hydroxyl and methylene,heat resistance is also affected.Therefore,the modified phenolic resin has become the core content of the study.At present,there have been previous studies on single or double elements of molybdenum,phosphorus,boron,and good results have been achieved.In order to further improve the toughness,heat resistance and adhesion of adhesive materials of phenolic resin,this paper mainly contains the following two aspects aiming at modification of thermoplastic phenolic resin: to use dopped phosphorus and boron to synthesize thermal plastic phenolic resin and study the effect on the performance with different contents of phosphate and boric acid;to modify by three elements of molybdenum,phosphorus and boron and to use orthogonal experimentto choose the optimal additive amount,so as to determine a resin binder formulation with not only high mechanical strength but also high chemical combination.Through analysis,conclusions are as follows:(1)The conversion rate of each formula was about 90% at 70? for 1 h,then at90? for 2 h.(2)When modified by adding phosphoric acid and boric acid,which were 1% and3% of phenol quality respectively,the properties of modified phenolic resin were the best: thermal decomposition temperature of 500 ?,hardness of 114 HA,bending strength of 51.76 MPa and impact strength of 0.15 J/cm2,increasing 25.9%?3.4%?17.6% and 114.3%,compared with nonmodified phenolic resin.(3)According to the orthogonal test method,preparation of modified thermoplastic phenolic resin with different molybdenum,phosphorus and boron contents has been investigated.It is a better formula with which the content of(NH4)2Mo O4,H3PO4,H3BO3 is 1%,1%,5% based on the mass of phenol,when its thermal decomposition temperature is 499 ?,residue carbon rate at 700 ? is 52.3%,bending strength is58.12 MPa and impact strength is 0.27J/cm2.