X-CT无损测试技术用于陶瓷涂层三维重构和孔隙率计算

doi:10.15541/jim20190534

摘要/Abstract

摘要：

陶瓷涂层对海工环境中的钢筋有着较好的保护作用。在碳钢表面喷涂磷酸盐陶瓷涂层, 采用XRD和XRF对陶瓷涂层的物相组成进行分析。结果表明: 实验用陶瓷的主要晶相成分为P₂O₅与SiO₂。采用SEM对陶瓷的表面和截面形貌进行观察, 发现陶瓷涂层内存在微裂纹, 涂层的厚度约为349 μm。采用X-CT测试可以得到陶瓷内部结构的高清图像, 并利用Matlab和Mimics软件对高清图像进行三维重构。此外通过阈值分割技术, 将CT图像内的孔与基体灰度值区分开来, 并计算得到陶瓷涂层的孔隙率为14%, 并采用压汞测试技术对测试结果进行验证。研究认为X-CT无损测试是一种建立陶瓷涂层内可视化孔结构分析的有效工具。

关键词: 陶瓷, 孔隙率, X-CT技术, 三维重构

Abstract:

Ceramic coatings can effectively prevent the corrosion of steel bars in marine environments. In this study, we prepared phosphate ceramic coatings on the surface of carbon steel. X-ray diffraction and X-ray fluorescence were used to analyze the phase structure and composition of the ceramic and the results show that the main crystal composition of ceramic is P₂O₅ and SiO₂. Scanning electron microscopy was used to characterize the morphology of the surface and the section and results showed that the surface was cracked, and the thickness of ceramic was 349 μm. Meanwhile, a number of high-resolution images of internal structure of solids were obtained by non-destructive X-ray computed tomography (X-CT). Matlab and Mimics software were used to conduct the three-dimensional reconstruction of the CT images. Matrix and holes are distinguished by threshold segmentation in grayscale images, and the porosity of the ceramic coatings was calculated to be 14.0%. In addition, mercury intrusion porosimetry was used to verify the calculation results. Therefore, X-CT can be a useful and reliable tool for the visualization of the internal structure of ceramic coatings.

Key words: ceramics, porosity, X-CT technology, 3D reconstruction

中图分类号:

TQ174

张志锋,王凤娟,武胜萍,蒋金洋. X-CT无损测试技术用于陶瓷涂层三维重构和孔隙率计算[J]. 无机材料学报, 2020, 35(9): 1059-1063.

ZHANG Zhifeng,WANG Fengjuan,WU Shengping,JIANG Jinyang. Three-dimensional Reconstruction and Porosity Calculation of Ceramic Coating: Nondestructive X-ray Computed Tomography[J]. Journal of Inorganic Materials, 2020, 35(9): 1059-1063.

图/表 7

Table 1 Composition of carbon steel Q235

Element	C	Mn	Si	S	P	Fe
Composition/wt%	0.14-0.22	0.30-0.65	<0.60	<0.05	<0.45	Balance

Fig. 1 XRD pattern of as-prepared ceramic coating

Table 2 Chemical analysis determined by XRF of the as-prepared ceramic coating

Oxide compound	Proportion/wt%
MgO	10.38
Al₂O₃	6.64
SiO₂	22.56
P₂O₅	29.75
K₂O	18.86
CaO	8.06
TiO₂	2.44
Balance (Na₂O/SO₃/Fe₂O₃/ZnO)	1.31

Fig. 2 Surface (a) and section (b) SEM images of the as-prepared ceramic coating Inset in (a) is the EDS analysis of area #1

Fig. 3 (a) TEM and (b) HRTEM images of ceramic coating

Fig. 4 CT image of ceramic coating (a) Raw X-CT image; (b, c) Threshold segmentation of (b) hole structure and (c) substrate structure; (d, e) 3D reconstruction of (d) hole and (e) substrate

Fig. 5 Pore size distribution test by MIP: cumulative intrusion (mL/g) and lg(differential intrusion/(mL?g-1))

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