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A STUDY ON THE FATIGUE RELIABILITY OF THERMALLY SPRAIED MATERIAL

热喷涂材料疲劳可靠性研究

基本信息

批准号：
07405008
负责人：
SHIMIZU Masao
金额：
$ 6.4万
依托单位：
KEIO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07405008/
关键词：
FATIGUE SURFACE MODIFICATION THERMAL SPRAYING FUSING POROSITY 再溶融処理溶射 Co基自溶合金疲労信頼性

项目摘要

Since a thermally sprayd coating has high wear, corrosion and heat resisance, it is used in many engineering fields for surface reinforcement and for repair of machine parts such as paper mill rolls, shafts and large bearings. With an increasing demand for the application of this process in several industries, it has become important to clarify the fatigue resistance of thermally sprayd steel. However, many problems remain unsolved concerning the fatigue properties of thermally sprayd coatings.In this study, the characteristics of the fatigue life of a thermally sprayd specimen with Co-based self-fluxing alloy were examined. The effects of the interface conditions on the sprayd specimen's fatigue strength were also studied. Rotational-bending fatigue tests were carried out to clarify the effect of post heat treatment (fusing treatment) on the fatigue strength of a sprayd specimen. The fatigue fracture mechanisms of thermally sprayd specimens were also examined using a Scanning Electron … More Microscope.The rusults are summarized as follows :(1) Fusing treatment temperature, heating rate and holding time strongly affect the characteristics of sprayd coatings such as configuration of microstructure, hardness and volume fraction of micro-pore (porosity).(2) Adhesion strength of thermally sprayd specimens which are fused by using a induction heating system is governed by mechanical interaction. Howver, in the case of a sprayd specimen fused by using a vacuum furnace, the diffusion of chemical elements strongly affects the characteristics of interface and adhesion strength.(3) There is considerable scatter in the value of porosity for torch-fused specimens. However, it is possible to achieve high quality coatings through well controlled fusing by using an induction heating system. In this case, the scatter of fatigue lives is much smaller than that of a torch-fused specimen.(4) The fatigue fracture mechanisms of thermally sprayd specimens are described as follows : (i) a crack start at the point of interface, (ii) the crack growth to the substrate (iii) the crack spreads from the interface in the sprayd coating and the entire coating fails rapidly (iv) the remaining part of substrate fails as a result of the coating failure. Less

由于热喷涂涂层具有高的耐磨性、腐蚀性和耐热性，因此它在许多工程领域中用于表面加固和机器部件的修复，例如造纸机辊、轴和大型轴承。随着该工艺在多个行业中应用的需求不断增加，阐明热喷涂钢的抗疲劳性变得非常重要。然而，热喷涂层的疲劳性能仍有许多问题没有得到解决，本文研究了钴基自熔合金热喷涂试样的疲劳寿命特性。研究了界面条件对喷涂试样疲劳强度的影响。进行旋转弯曲疲劳试验，以澄清后热处理（熔融处理）对疲劳强度的喷涂试样的效果。用扫描电子显微镜研究了热喷涂试样的疲劳断裂机制 ...更多信息结果表明：（1）熔凝处理温度、升温速率和保温时间对涂层的显微结构、硬度和孔隙率等性能有显著影响。(2)采用感应加热系统熔化的热喷涂试样的粘附强度受机械相互作用的影响。而在真空炉熔制的喷涂试样中，化学元素的扩散对界面特性和结合强度有很大的影响。(3)火炬熔融试样的孔隙度值有相当大的分散性。然而，通过使用感应加热系统，可以通过良好控制的熔融来实现高质量的涂层。在这种情况下，疲劳寿命的分散是远远小于火炬熔融试样。(4)热喷涂试样的疲劳断裂机制如下：（i）裂纹起始于界面处;（ii）裂纹扩展到基体;（iii）裂纹从界面处扩展到整个涂层;（iv）基体的剩余部分由于涂层失效而失效。少