The Study Of The Principle And Inhibition Of Tungsten Carbide Leaching From Cemented Carbide Tools

The additives in the cutting fluid could lead to the tungsten carbide leaching, whichcould not only reduce cemented carbide tool life and waste resources, but also couldproduce asthma, pulmonary fibrosis and allergic dermatitis. In order to research thepHenomenon of the tungsten carbide leaching in the cutting process, the test choose somecommonly used inorganic additives and organic additives, and investigate their impact tothe tungsten carbide leaching and analysis the leaching mechanism,in addition, wesynthesis effective inhibitors to impede oxidation dissolution of tungsten carbide.The immersion test of carbide blade in the aqueous solution showed that, the surfaceof carbide blade appear abundant pits, add sodium carbonate solution, tungsten leachingseriously and pH decline. The experimental studies have shown that, tungsten carbidewill generate tungsten trioxide, some tungsten trioxide covered on the surface of theblade, after adding sodium carbonate, because the price of tungsten6has a highionization potential and a good ability to attract the ligand, thus tungsten carboxylategenerated in the sodium carbonate solution, and aggravate the tungsten leaching.In order to effectively suppress the tungsten leaching, we researched the differentadditives on the tungsten leaching, and the results showed that borax is anodic inhibitor,through inhibit the anodic reaction to reduce the tungsten leaching; oleic acidtriethanolamine is an adsorption-type inhibitor, hydroxyl and carboxyl (polar groups)adsorbed on the blade surface, while a longer carbon chain (non-polar groups) separatethe blade and external media, inhibit the oxidation dissolved of tungsten effectively;benzotriazole is a nitrogen-heterocyclic compound, and it has good electron-withdrawingability due to the lone pair of electrons, and form coordination compounds adsorbed onthe blade surface with the empty orbital of cobalt, inhibiting the oxidation dissolved oftungsten. By orthogonal test, the study found that the complex of borax, oleic acid,triethanolamine and benzotriazole has good inhibition for the tungsten leaching, while thegrinding experiments of carbide blade with grinding wheel and friction experiments ofcarbide blade with steel were verified three compounds which can inhibit tungstenleaching.The selection of cutting fluid additives which could inhibit the tungsten leachingeffectively, not only could extend tool life, reduce costs and protect the environment, butalso could protect the health of the operator, and reflect the people-oriented thinking.