Study on Technology of Dynamic Copper Pipe Corrosion Method Foraluminumalloy Casting with Slender and Complex Holes
|School||Nanchang University of Aeronautics and|
|Keywords||Embedded copper pipe ZL114A aluminum alloy dynamic corrosion slender and complex holes|
In recent years, castings in the aviation industry tend to be of thinner wall, morecomplicated, more precise, and more integrated and thus the quality requirement ofcasting is getting higher. The oil holes of shell parts of one type of aeroengine areslender and complex. the traditional manufacturing process is not only difficult tomeet the requirements of quality, precision and performance, but also long inmanufacturing cycle and extremely high in cost. In this paper, a technology ofembedded copper pipe for slender holes was adopted to fabricate aluminum alloy testelements with complex slender holes. An independently developed dynamic copperpipe corrosive device was adopted to systematically investigate the process ofdynamic copper pipe corrosion. In factory production, the dynamic copper pipecorrosion process was applied to successfully corrode the shell parts with slenderholes. An analysis of X ray detection and split-method inspections shows that thecorrosion effect is excellent. The influencing rules of corrosion liquid concentrationand corrosion time on ZL114A aluminum alloy matrix were also systematicallystudied. The main achievements and conclusions are as follows.The independently developed dynamic copper pipe corrosive device makescorrosive liquid flows and thus corrodes copper pipes dynamically which distinctlyincreases corrosion efficiency. The ZL114A aluminum alloy matrix can be protectedfrom corrosion since corrosive liquid can hardly contact with the matrix. Moreover,corrosion liquid can smoothly flows into the copper pipe due to the interface designedbetween the copper pipe and plastic conduit.In this paper, for ZL114A aluminum alloy samples, the copper pipes of differentstructures and Φ4~6mm in diameter,1.0mm thick,450mm long were corrodedcompletely within2hours in the corrosion liquid of45~50%HNO3.The ZL114Aaluminum alloy matrix appeared a loss of weight within2hours when theconcentration of corrosion liquid was lower than30%HNO3, which indicates that thealuminum alloy matrix can be corroded by HNO3. However, the aluminum alloymatrix maintained its weight within2hours when the concentration of corrosionliquid was higher than45%HNO3. It shows that the aluminum alloy matrix wasprevented from corroding in concentrated nitric acid since a protective film has been formed on the interface of the aluminum alloy. As a result, the concentration ofcorrosion liquid must be controlled between45%~50%in a copper pipe corrosiontest.According to the industry test of using dynamic corrosion device to corrodeZL114Aaluminium alloy shell parts, as long as the corrosion liquid can smoothly flow,copper pipes with wall thickness less than1.0mm were corroded completely within2hours in45-50wt%nitric acid.