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我厂产品231化油器上有一小零件叫怠速调节螺钉,要求液体软氮化(以尿素为原料)后镀锌,多年来一直很难镀锌,必须经长时间的酸洗和滚镀,有时半天只能出一次活,经常出现尺寸超差报废现象,就是勉强镀上,氮化层也已经不存在了。后来我们分析,软氮化后的零件难以镀锌,是因为氮化过程工件有氢渗入,改变了工件表面的电极电位,我们在软氮化后加一道除氢工艺(200～250℃2小时),再镀就和未氮化一样好镀了,只要20～30分钟就可镀好。
Our factory product 231 carburetor has a small part called idle speed adjustment screw, requiring liquid nitrocarburizing (with urea as raw material) after galvanizing, it has been difficult to galvanize for many years and must be pickled and barrel-plated for a long time, Sometimes only a half-day out of work, the phenomenon often oversized scrapped, barely plated, nitride layer also does not exist. Later, we analyzed that the parts after nitrocarburizing are difficult to galvanize because the nitriding process has the infiltration of hydrogen and changes the electrode potential on the surface of the workpiece. After the nitriding, we add a hydrogen removal process (200-250 ° C for 2 hours ), And then coated on the same as the non-nitriding plated, as long as 20 to 30 minutes can be plated.