Ceramic processing is becoming more and more sophisticated

Ceramics have some properties that other materials do not have, such as wear resistance, high temperature resistance, corrosion resistance, as well as excellent electrical, magnetic, acoustic, optical and other physical characteristics. Therefore, it has broad application prospects in energy, electronics, aerospace, machinery, automotive, metallurgy, and biology, and becomes an indispensable key material for industrial technology, especially cutting-edge technology. However, ceramic materials are easily broken and cracks are easily diffused. This fatal weakness seriously restricts the processing, development, and application of ceramic materials.

Special ceramics show their popularity

In November 2010, the 8th China International Aerospace Exhibition was held in Zhuhai. As the largest aerospace exhibition in China, it attracted great attention from all over the world. At the exhibition, a large number of new products representing the country’s level in this field have been showcased, including J-10, H-6, and C919. Less well-known is that the ceramic industry is also closely related to this, among which special ceramics are widely used in these aerospace equipment. In this air show, special ceramic applications involved helicopter armored ceramics, aircraft brake disc materials, satellite battery ceramic diaphragm materials, infrared stealth/camouflage, ceramic bearings, ceramic radome materials, etc. Ceramics are widely used in this field because of their unique advantages.

Ceramics are a class of raw materials with rich sources, long traditions, and a series of excellent properties such as rigidity and durability. The history of human use of ceramics has been for thousands of years. Today, ceramic products have reached every aspect of people's production and life. The ceramic industry has also become an industry that cannot be ignored in modernization.

Ceramic products can be divided into two major categories, namely ordinary ceramics and specialty ceramics. Ordinary ceramics are the ceramics that we understand in traditional concepts. This kind of ceramic products is the most common and used in people's life and production. Special ceramics are used in various modern industry and cutting-edge science and technology ceramic products. The raw materials used and the required production technology have been quite different from ordinary ceramics. Special ceramics can be further subdivided into ceramics and functional ceramics for structural materials based on their properties and applications. Ceramics for structural materials are mainly used for wear resistance, high strength, heat resistance, thermal shock resistance, hardness, high rigidity, low thermal expansion, and thermal insulation. Functional ceramics include ceramic products and materials such as electromagnetic functions, optical functions, and biological-chemical functions, as well as nuclear ceramics and other functional materials.

Special ceramics are manufactured using optimized formulas and fine production processes. Their excellent mechanical and physical properties are unmatched by metallic materials. In the 1970s and 1980s, special ceramics have emerged in electronic and optical high-tech devices. With the rapid development of modern science and technology, people have higher and stricter requirements for materials. As a special ceramic with excellent performance, it has emerged in many modern defense industries and cutting-edge science and technology fields. Such as aviation, aerospace, semiconductor, high-frequency technology, high-temperature materials and a variety of special-purpose new materials, new components without special ceramic materials.

Processing technology bottlenecks

Ceramic materials are brittle, easily broken, and the cracks are prone to spread. This fatal weakness seriously restricts the processing, development, and application of ceramic materials. With the development and application of special ceramic materials, the requirements for the processing of ceramic materials have become higher and higher, and the processing technology has also received widespread attention.

"In the processing of ceramic materials, grinding is an important method of precision machining. It can be divided into three categories of removal processing, combined processing and deformation processing." Yuan Julong said, "In the process of precision or ultra-precision machining, such as removal processing To remove a layer of atoms on the surface of a material is to cut the material's surface atoms and internal atoms, mechanical processing will inevitably leave processing and deteriorating layers, and processing will also be accompanied by chemical reactions and other complex phenomena. Failure to handle it will affect the performance of the material. ."

According to reports, ultra-precision machining of ceramic materials is a necessary means to achieve high shape accuracy, surface accuracy and surface integrity. In recent years, although China has done a lot of work on ultra-precision processing, it is still far away from developed countries. At present, China's large-diameter, high-quality ball or rely on imports, but foreign countries are not willing to sell to us, resulting in China's large-scale fans and other applications are subject to certain restrictions.

“The factors that affect precision machining and ultra-precision machining are mainly the processing mechanism, processed materials, processing equipment and its basic components, processing tools, detection and error compensation, work environment, process design, fixture design, and human skills. Precision machining methods include ultra-precision cutting, ultra-precision grinding, ultra-precision grinding and polishing, and special machining, among which there are many basic scientific issues that need to be resolved.We currently focus on the basic geometric surfaces (plane, spherical, cylindrical). Ultra-precision, high-efficiency grinding, grinding and polishing processing technology and equipment, and the development of a series of original processing methods, key technologies, processing and inspection equipment, and the formation of processing technology and theoretical systems, and applied to the actual project.” Yuan Julong said.

Assist ceramic precision machining

Under the support of the National Natural Science Foundation of the People's Republic of China, Yuan Julong's team proposed a new method for semi-fixed abrasive grain processing and semi-fixed abrasive tool design techniques with low bonding strength and weak plastic deformation, revealing advanced ceramic materials in the brittle and plastic domains, respectively. The processing rules for uniform removal of elastic domains were developed; semi-fixed abrasive tools with low bonding strength and weak plastic deformation characteristics were developed, and their performance testing and evaluation systems were established. They proposed the principles of eccentric ball milling and dual-rotation grinding with two kinds of spherical full-enveloping grinding balls to provide a theoretical basis for solving the technical problems of low ball-forming accuracy and low ball-forming efficiency. A quantitative analysis method for ball-surface grinding uniformity was established. It provides an effective forecasting method for the optimization of sphere processing technology. The team developed a ceramic ball processing expert database and a ball-fixed abrasive grinding technology, chemical-mechanical polishing technology, grinding disk in place trim and other ceramic ball precision and efficient processing of key technologies, forming a new method of ceramic ball precision and efficient batch processing technology, and A new precision ball grinder based on full envelope milling and balling was developed to achieve batch and efficient machining of ceramic balls.

During the implementation of the project, the research team published 58 academic papers, among which more than 80 were received by SCI and EI; 4 were invited reports at international conferences; 2 was awarded the second prize of National Science and Technology Progress Award; 1 first prize, 1 second prize, 1 third prize; 14 invention patents applied, 5 invention patents, 5 software copyrights; and extensive international academic exchanges, training a batch of Doctoral students and master students. In the evaluation of the project's conclusion, a team of 7 experts led by Ren Luquan, academician of the Chinese Academy of Sciences, and Tan Jianrong, an academician of the Chinese Academy of Engineering, gave high appraisal to the project and the overall evaluation was excellent.