材料热膨胀系数非一致性的原因

在精密测量和精密工程技术领域，影响精度的众多因素中，温度变化引起的热变形误差所占的比重越来越大，因此对热误差修正的好坏直接影响着精度。各种手册或工具书中提供的材料热膨胀系数一致性较差，给正确引用带来了困难。为此，系统地分析了造成这种非一致性的主要原因，指出热膨胀系数定义的差异，测量方法的差异，试样化学成分、加工方法和形体尺寸的差异是造成各种手册或工具书上热膨胀系数非一致性的主要原因。该研究为在工程实际中选用恰当的材料热膨胀系数提供了依据。

Reasons for inconsistency of material thermal expansion coefficient

In the field of precision measurement and precision engineering, thermal errors due to temperature changes are plying an increasingly dominant role among errors incurred by factors affecting the precision. As a result, a better correction of thermal errors exerts a direct effect on the overall precision of system. But the occurrence of inconsistency in the available data of thermal expansion coefficients of various materials in relevant handbooks and reference books discourages the correction of the thermal errors. This paper highlights an analysis of fundamental reasons for the inconsistency, such as the differences in the definition of thermal expansion coefficient, measuring method and chemical composition, processing method, size and shape of the sample, and the mechanism of how each factor affects the data. This paper provides a reference for the proper selection of thermal expansion coefficients in engineering practice.