| 摘要 |
A method is disclosed for making an article, such as a cylinder head, having one or more hollow ceramic tubes, such as ceramic exhaust port liners, cast in-situ therein with reduced cracking or breakage of the ceramic tube from tensile and compressive stresses exerted on the ceramic tube during the casting process. The method involves forming a removable core in the ceramic tube of a core material having a thermal expansion coefficient not exceeding about 10 times that of the ceramic tube to minimize crack-causing differential thermal expansion-induced tensile stresses on the ceramic tube when molten metal is cast therearound, casting the molten metal about the cored ceramic tube in a mold cavity, stress relieving the cast article at an elevated temperature before the cast article cools to a lower temperature at which crack-causing differential thermal contraction-induced compressive stresses are exerted on the cast in-situ ceramic tube, and removing the core from the cast article.
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