High-Purity Alumina Ceramics: The Key 'Ceramic' in Four Major Fields, Showcasing the Charm of 'Purity'
High-purity alumina Ceramics Are important ceramic materials primarily composed of high-purity ultra-fine alumina, with α-Al2O3 as the main crystalline phase. Due to their excellent properties such as high mechanical strength, great hardness, high-temperature resistance, and corrosion resistance, high-purity alumina ceramics are widely used in various fields including machinery, electronics, integrated circuits, and medicine.
Precision components for semiconductor equipment
It is understood that a large number of precision Ceramic Components are used in semiconductor equipment, and these ceramic parts can account for more than 10% of the cost of semiconductor equipment, among which alumina ceramic is a commonly used ceramic material for precision components.
For example, in semiconductor etching equipment, the material of the etching chamber is a primary source of wafer contamination. The extent of the impact of plasma etching on it determines the yield, quality, and stability of the etching process of the wafer, among other factors. Therefore, researching and developing an extremely etch-resistant chamber material has become a highly challenging task in the semiconductor integration industry and plasma etching technology. Currently, high-purity Al2O3 coatings or Al2O3 ceramics are mainly used as protective materials for etching chambers and internal chamber components. In addition to the chamber, high-purity alumina ceramics are also required for gas nozzles, gas distribution plates, and fixed rings that secure the wafer in plasma equipment. Furthermore, in wafer polishing processes, alumina ceramics can be widely applied to polishing plates, polishing pad correction platforms, vacuum suction cups, etc.
Machinery
High purity alumina ceramics possess excellent mechanical properties. Using conventional pressure sintering methods, alumina ceramics can be prepared with a flexural strength of approximately 250 MPa, while high purity alumina ceramics produced via hot pressing sintering can achieve a flexural strength of up to 500 MPa and a hardness of 9 GPa (Mohs hardness). Due to these characteristics, high purity alumina ceramics can be utilized as grinding wheels and ceramic nails, among which high purity alumina ceramic tools and high purity alumina Ceramic Balls are the most widely applied. However, because high purity alumina ceramics exhibit relatively poor fracture toughness and thermal shock resistance, it is often necessary to introduce a second phase, such as ZrO2, into the alumina to enhance the toughness and thermal shock resistance of the high purity alumina ceramic materials. Additionally, by refining the grain size to produce high purity alumina ceramics with small and uniformly distributed grain sizes, significant improvements in strength and toughness can also be achieved to a certain extent.
Electronics and Electric Power
High-purity alumina ceramics exhibit low high-frequency dielectric loss and excellent insulation properties, making them suitable for the preparation of insulating devices, ceramic substrates, and transparent alumina ceramics. Among these, ceramic substrates and transparent alumina ceramics are widely used and have seen increasing applications in various specialized optical instruments, lighting equipment, and space satellite devices.
In the realm of ceramic substrates, alumina ceramic substrates are the most prevalent substrate materials utilized in modern electronic information industries, serving as the foundational material for integrated circuit chips. For instance, within the domain of LED lighting, the thermal expansion coefficients of mainstream substrates typically range from 14 to 17×10^-6/K. Under conditions characterized by substantial temperature variations and rapid thermal fluctuations, printed circuit boards (PCBs) tend to experience greater expansion compared to chip packaging, resulting in soldering complications. In response to these challenges, alumina ceramic substrates possess a thermal expansion coefficient that is significantly closer to that of the chip, effectively alleviating such issues.
In the field of transparent alumina ceramics, since Dr. Coble first developed and prepared transparent alumina ceramics (also known as transparent polycrystalline alumina ceramics) in 1959, substantial attention has been given to the research and application of transparent alumina ceramics. Compared to glass, transparent alumina ceramics exhibit higher strength, hardness, and toughness, and their excellent resistance to surface wear also surpasses that of glass. Additionally, in comparison to single crystal materials, the preparation temperature for transparent alumina ceramics is lower and the production cycle is shorter. It is these properties that have made transparent alumina ceramics a focal point of research, leading to extensive applications in the fields of optics, special instrumentation, lighting, electronics, high-temperature technology, national defense and military, as well as aerospace. For instance, the light transmission, corrosion resistance, and high-temperature stability of transparent alumina ceramics allow for their fabrication into luminescent arc tubes used in high-pressure sodium lamps.
Medical
Biomedical materials can repair human physiological functions without producing adverse characteristics in the human body, and medical health organizations impose very strict requirements on biomedical materials. These materials must not only possess biocompatibility but also exhibit non-toxicity, environmental friendliness, and durability. High-purity alumina ceramics are widely recognized in clinical and research settings for their excellent biocompatibility, mechanical properties, and chemical stability, making them suitable for implantation without causing rejection reactions. They can be extensively used in the preparation of artificial bones, bolts, and artificial joints. The distinction of high-purity alumina ceramics from ordinary alumina ceramics lies in their high purity, which, along with stringent requirements for particle size and dispersion, poses a significant challenge for the preparation of high-purity alumina powders.