就是你说的这种情况,500C预热后防渗的地方完全防不住,我们在用condursal0090防渗剂时就碰到过同样情况,该防渗剂是用二甲苯做溶剂的,截取原文说明书给你:
Do not preheat coated parts at temperatures exceeding 350° F with oxygen present. Both contact with water and oxidizing of the paint may cause run-off problems during the carburizing process to follow.
你自己可以去网上找有关这个防渗剂的使用说明。