Influences on Quantitative Nitriding Layer Thickness Measurements using Model-Based Photothermal Radiometry

IF 0.3 Q4 THERMODYNAMICS
M. Mikulewitsch, J. Dong, D. Stöbener, J. Épp, A. Fischer
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引用次数: 1

Abstract

Abstract In nitriding furnaces, the nitriding result is currently only controlled indirectly via the nitriding potential based on gas sensors. Detrimental properties such as soft spots, insufficient compound layer thickness or strongly porous zones, which might result from reduced surface reactivity, are thus only detected post-process. Therefore, in-process measurements of the layer formation promise a real benefit for energy efficiency and process quality enhancement. Photothermal radiometry is a promising contactless method for layer inspection that so far showed qualitative correlations of the photothermal phase signal with material parameters and layer thicknesses. In this article, thickness and thermal conductivity of the compound layer are quantitatively determined by using a physical signal model for a least-squares approximation of in-process measured photothermal phase signals. In addition, the influence of roughness and surface curvature is investigated, with the model-based photothermal layer thickness measurement showing robustness to different surface conditions and allowing quantification of the layer thickness with uncertainties < 1 μm even during in-process measurement inside an industrial nitriding furnace.
基于模型的光热辐射法对定量氮化层厚度测量的影响
摘要在渗氮炉中,目前仅通过基于气体传感器的渗氮电位间接控制渗氮效果。诸如软点、复合层厚度不足或强多孔区等有害特性可能是由于表面反应性降低而导致的,因此只有在处理后才能检测到。因此,在过程中测量层的形成对能源效率和工艺质量的提高有真正的好处。光热辐射测量法是一种很有前途的非接触式层检测方法,迄今为止,光热相位信号与材料参数和层厚度之间存在定性的相关性。在本文中,通过使用物理信号模型对过程中测量的光热相位信号进行最小二乘近似,定量地确定了复合层的厚度和导热系数。此外,研究了粗糙度和表面曲率的影响,基于模型的光热层厚度测量显示出对不同表面条件的鲁棒性,并且即使在工业氮化炉内的过程测量中,也可以在不确定度< 1 μm的情况下量化层厚度。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
CiteScore
1.50
自引率
33.30%
发文量
43
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