Abstract

The change in the microhardness over the thickness of samples made of EDT-69N binder cured in vacuum and at atmospheric pressure at temperatures from 130 to 170°C was investigated. It was found that the change in microhardness along the thickness of the samples occurs according to a parabolic law, with the maximum values being achieved in the middle of the sample cross section along the thickness. With an increase in the molding temperature, the microhardness in the middle section of the sample increases from 222 MPa at a molding temperature of 130°C to 410 MPa during molding at 170°C. At the critical molding temperature (170°C), the microhardness in all zones of the specimen cross section (subsurface, semi-average, and core) levels off, while the parabolic dependence degenerates into a straight line. It is shown that the method of scratching (sclerometry) demonstrated a fairly high sensitivity to the state of samples cured at different temperatures. With an increase in the molding temperature, the width of the sclerometric grooves decreases. At the critical molding temperature of 170°C, the groove width is stabilized and becomes constant throughout the sample thickness. To characterize the difference in the values of the microhardness of the cured binder in the sample volume, it is proposed to use a dimensionless “coefficient of volume anisotropy,” which can take a positive, negative, or zero value. With an increase in the curing temperature of the binder and, accordingly, with an increase in the microhardness of the sample, the coefficient of volume anisotropy decreases, and when the samples are molded at the critical temperature, it goes to zero, which indicates the absence of anisotropy.

中文翻译：

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不同温度固化EDT-69N粘合剂体积显微硬度变化规律

摘要

研究了由 EDT-69N 粘合剂制成的样品在真空和大气压下在 130 到 170°C 的温度下固化的显微硬度随厚度的变化。发现沿样品厚度的显微硬度变化根据抛物线规律发生，最大值出现在沿厚度样品横截面的中间。随着成型温度的升高，试样中间段的显微硬度从成型温度130℃时的222 MPa增加到170℃成型时的410 MPa。在临界成型温度 (170°C) 下，试样横截面所有区域（次表面、半平均和核心）的显微硬度趋于平稳，而抛物线相关性退化为一条直线。结果表明，刮擦法（硬化法）对不同温度下固化的样品状态表现出相当高的敏感性。随着成型温度的升高，硬化槽的宽度减小。在 170°C 的临界成型温度下，凹槽宽度稳定并在整个样品厚度上保持恒定。为了表征样品体积中固化粘合剂的显微硬度值的差异，建议使用无量纲的“体积各向异性系数”，它可以取正值、负值或零值。随着粘结剂固化温度的升高，相应地随着试样显微硬度的增加，体积各向异性系数减小，当试样在临界温度成型时，