High-throughput Materials Service Evaluation
High-throughput Materials Service Evaluation
Lijie Qiao Professor at the University of Science and Technology Beijing, Distinguished Young Scholar of China, Changjiang Distinguished Professor
Kewei Gao Professor at the University of Science and Technology Beijing, Project Leader of the National Key Research and Development Program
Lei Gao Associate Researcher at the University of Science and Technology Beijing
【Chief members】
Lijie Qiao Professor at the University of Science and Technology Beijing
Kewei Gao Professor at the University of Science and Technology Beijing
Lei Gao Associate Researcher at the University of Science and Technology Beijing
【Research Background】
During the service life of a material, owing to the influence of the surrounding environment, environmental failures of the material are often inevitable, leading to serious accidents and significant losses to the national economy. Therefore, research on the mechanism of material environmental failure (such as hydrogen embrittlement, stress corrosion, friction, and wear) is of great significance in improving the stability and reliability of materials when used in the environment.
【Research Objectives】
The material environmental service behavior team targets the issues of significant environmental variation and multiplicity of material types during the failure of structural and functional engineering materials. By conducting research on the mechanism and evaluation techniques of a material’s environmental failure through high-throughput experiments and computing technologies, the team aims to overcome the problems of existing evaluation techniques, such as difficult operation and low efficiency. In addition, by developing a key evaluation technology for the serviceability of composite material chips, a technology to study the evolution patterns of the stress–strain field during the initiation of multiple parallel cracks, a high-throughput computer simulation technology for the environmental fracture of materials, and a high-throughput screening technology for the micro- and nano-scale surface protective coating of functional materials, the team can establish a highly efficient generic technology to evaluate the environmental failure of materials. These achievements will help in breaking through the technical bottleneck of a “high throughput evaluation of the service behavior,” shortening the duration of the environmental failure evaluation process by half.
【Main Research Areas】
1. Development of a fast evaluation technology for the serviceability of composite material chips.
2. Development of a high-throughput evaluation technology for the sensitivity of environmental failure.
3. Development of a high-throughput characterization technology for the continuous distribution of stress fields.
4. High-throughput calculations to investigate the anodic dissolution behavior of metal surfaces.
5. High-throughput calculations to investigate the characteristics of a passivation film on metal surfaces.
6. Develop a fast high-throughput screening technology for a surface protective coating of metals.
【Significant Research Progress】
1. Research on the mechanism of film-induced cracking of toughness matrices
Coatings are commonly used to protect material matrices used in harsh environments. However, they will also reduce the fatigue life of the materials to a different extent, which significantly restricts their application. By investigating the initiation of multiple parallel cracks on ceramic films, we found that the cracking of a TiN film or WC-10%Co-4%Cr coating can lead to the cleavage cracking of the toughness matrices (such as in pure iron, AISI 1020 steel, brass, and austenitic stainless steel), as shown in Fig. 1. Based on the cleavage fracture and a dynamic fracture analysis, we established a membrane-induced matrix damage mechanism to explain how hard films reduce the fatigue property of metallic matrices, thereby providing a theoretical basis for the preparation of coating systems that improve the wear and corrosion resistances without compromising the fatigue property of the material.
Figure 1(a): Cracking of 1-μm thick TiN film leading to cracking of a brass matrix, and (b) cracking of 250-μm thick WC-10%Co-4%Cr coating leading to cleavage cracking of the iron matrix.
2. High-throughput calculations based on first principles to investigate characteristics of passivation film on metal surfaces
Passivation films, typically dense oxide films, can effectively protect a matrix material. However, owing to the complexity of their structures, compositions, and properties, there are no unified passivation film theories that can explain all passivation behaviors. Therefore, further research on the relevant theories of passivation films is necessary. Through first principles, we have conducted highly thorough calculations to study the effects of the vacancy defects, doping elements, and adatoms on the characteristics of an oxide film, from which we have identified the principles of the interactions of different oxide films and their interfaces with hydrogen atoms. In addition, by conducting high-throughput calculations based on first principles, we have analyzed the stability and electron transport properties of oxide films, and successfully revealed the mechanisms of their cracking and failure, thereby providing theoretical guidance for improving the properties of passivation films to more effectively protect the matrix materials.
Figure 2 (a) Atomic structure of a Cr2O3/Fe2O3 interface, (b) schematic diagram of the capture of H atoms by the octahedral interstice at the center of the Cr2O3/Fe2O3 interface, and (c) effects of different defects capturing an H atom on the work function.
