Study Of Automatic Copper Alloy Brazing Procedure On The Sealing Surface Of Cast Iron Wing Valve

As copper alloy has good scratch resistance and good resistance to marine and atmospheric corrosion, it is widely used in the manufacture of valve sealing surface. At present the copper alloy on the sealing surface of cast iron valve, is deposited by two ways: the manual oxyacetylene brazing which is inefficient, and the plasma arc powder surfacing which is costly. By contrast, induction brazing is efficient, cheap and fit for automation; argon arc brazing has coatings with good forming and great performance, and it is efficient and easy to achieve automation. So they could be used in the deposition of copper alloy on the sealing surface of cast iron valve.In this paper induction brazing and argon arc brazing were used in the deposition of copper alloy on the sealing surface of cast iron valve, and their brazing procedures were studied respectively. After experiments it can be seen that the best induction brazing procedure is with 8mm induction distance, 60A (10s) combined with 100A (25s) and the flux with 65% borax +15% Na3PO4+20% Na2CO3. The best induction brazing procedure is with 130A current, 16V arc voltage, 30cm/min brazing speed and 88.2cm/min wire feeding rate. And it was found that the coatings of induction brazing and argon arc brazing both have great microstructures and performances. Then the two brazing methods were compared to the manual oxyacetylene brazing method, it was seen that induction brazing and argon arc brazing can both lower the cost and increase the efficiency, while induction brazing has great efficiency and argon arc brazing is very easy to achieve automation. As a result, it was concluded that induction brazing and argon arc brazing have their own advantages respectively in the automatic brazing of copper alloy on the sealing surface of cast iron valve.In the induction brazing copper alloy was innovatively added in the form of wire, which can greatly reduce the cost. Besides, the composition of flux used in induction brazing was optimized. And in the argon arc brazing, it can be certain that the matrix cast iron is hardly melted, and the problem of iron exposure in the coatings has been solved.