发动机凸轮轴衬套合金层表面白斑成因分析

王恒¹，李杨¹，胡志芹¹，伍云²，赵亚斌³，周聪¹

1.磐固合金（常州）有限公司，江苏 常州  213399；2.二重（德阳）重型装备有限公司，四川 德阳  618000;

3.苏州纽威阀门股份有限公司，江苏 苏州  215004

摘要：为解决某柴油机凸轮轴衬套AlSn6CuNi合金层表面出现的大量白斑，利用白光干涉仪、X射线衍射仪、X射线荧光光谱仪、扫描电子显微镜和能谱仪，分析合金层表面三维形貌、表面物相、合金成分、微观组织形态和元素成分强度，确定白斑形成原因。结果表明：白斑附着在合金层表面，主要成分为Si；对比无白斑合金，白斑合金层中Sn质量分数减小，Al质量分数增大，白斑合金层表面、微观组织致密性较差，有明显的坑洞，白斑区域外表面有一定的Si、Ca、Na等元素，确定白斑产生的原因为热处理退火温度较高造成部分Sn熔化流出，合金层表面形成坑洞缺陷，引发表面微裂纹，使浸泡过程中清洗剂中的硅酸钠黏附在合金层表面。为获得良好的合金层组织性能，应严格按照生产工艺控制合金层退火温度。

关键词：凸轮轴衬套；AlSn6CuNi合金层；白斑；热处理退火温度

Analysis of the causes of white spots on the surface ofalloy layer of engine camshaft bearing

WANG Heng¹, LI Yang¹, HU Zhiqin¹, WU Yun², ZHAO Yabin³, ZHOU Cong¹

1.Milestone Metal (Changzhou) Co., Ltd., Changzhou 213399, China;

2.Erzhong (Deyang) Heavy Equipment Co., Ltd., Deyang 618000, China;

3.Neway Valve（Suzhou）Co., Ltd., Suzhou 215004, China

Abstract: To address the issue of numerous white spots on the surface of the AlSn6CuNi alloy layer of a certain diesel engine camshaft bearing, a comprehensive analysis is conducted using white light interferometry, X-ray diffraction, X-ray fluorescence spectroscopy, scanning electron microscopy, and energy dispersive spectroscopy. The analysis focuses on the three-dimensional morphology, phase composition, alloy composition, microstructural characteristics, and elemental intensity of the alloy layer surface to determine the cause of the white spots. The results indicate that the white spots adhered to the surface of the alloy layer is primarily consisting of Si. Compare to the alloy without white spots, the Sn mass fraction in the alloy layer with white spots decrease, while the Al mass fraction increase. The surface and microstructure of the white spot alloy layer exhibit poor density and significant pitting. The outer surface of the white spot area contains certain elements such as Si, Ca, and Na. It is determined that the formation of the white spots are due to the high annealing temperature during heat treatment, which cause partial melting and leakage of Sn, resulting in pitting defects on the alloy layer surface and leading to micro-cracks. This allows sodium silicate from the cleaning agent to adhere to the surface during the soaking process. To achieve good organizational performance of the alloy layer, it is essential to strictly control the annealing temperature according to the production process.

Keywords: camshaft bearing; AlSn6CuNi alloy layer; white spot; heat treatment annealing temperature