“The raw material of silicon nitride is this gray-black silicon powder, and the synthesized silicon nitride can be made into such a pure white color, indicating that the impurity is extremely low, and there is no first-class technology to do this.”
Recently, in the exhibition hall of QDCX Advanced Ceramic Materials Technology Corporation, QDCX’s CTO Dr. Jia pointed to two bottles of display samples, one black and one white, to introduce the Hay Think team.
Silicon nitride is a new type of structural ceramic material, which has the characteristics of high strength, low density, high temperature resistance, corrosion resistance, and self-lubricating. It is called “the king of structural ceramics”.
In the past, China could only produce low-end silicon nitride powder, and high-end silicon nitride powder was monopolized by a few companies in Japan, Germany and other countries, and the price was expensive.
QDCX broke the monopoly through joint research and development with the Chinese Academy of Sciences and Tsinghua University, synthesized high-performance silicon nitride powder, and exported it to many developed markets, growing into an industry leader.
Choosing the most technically difficult path
“We started doing research on silicon nitride as early as 2008. When the CTO of QDCX was studying for a PhD at Tsinghua University, he started to research new silicon nitride materials with the support of his post-doctoral co-supervisor and academician Cheng Huiming of the Chinese Academy of Sciences.” At that time, high-end silicon nitride was completely monopolized by foreign companies, and no company in China could make it. However, the demand for high-end silicon nitride powder in electric vehicles, high-speed railways, airplanes, wind power and other fields is increasing.
China has always listed high-performance silicon nitride powder preparation technology as a key research plan, and QDCX has established a research and development team based on the State Key Laboratory of Advanced Ceramics and Fine Technology of Tsinghua University, determined to overcome this difficulty. “
There are three representative production methods for silicon nitride powder:
The first is the thermal decomposition method, which is a large chemical process with high product purity and fine particle size, but the process is complicated;
The second is the silicon powder nitriding method, which has low technical difficulty and good response control, but high energy consumption and high cost;
The third is the combustion synthesis method, which has high product purity, simple equipment, low energy consumption and high production efficiency, but it is extremely technically difficult and difficult to control.
“The first method requires a lot of investment and cannot be done at the start-up stage. The second method consumes a lot of energy and has no future prospects.
QDCX comprehensively considered the third road with the most technical difficulty.
At that time, the combustion synthesis method had no precedent for large-scale production in the world, and only one company in China was doing it, and it could only produce low-end silicon nitride powder.
“The combustion synthesis method is simply to put the raw materials and auxiliary materials formula into the reaction kettle to ignite, and let it synthesize silicon nitride in natural combustion. This method can produce a furnace in 2 to 4 hours, temperature and pressure The changes in the kettle are extremely rapid, and real-time adjustments must be made to make the temperature and pressure fluctuations of the reaction kettle small to synthesize high-quality silicon nitride, which is very difficult to control.
Dr. Jia told reporters that the alpha phase must exceed 92% and the oxygen content must be controlled within 0.8% to be considered high-end silicon nitride standards. It took them 5 years to successfully experiment in a small 5-liter reactor. Master the control technology, parameters and various formulas.
After the laboratory was successfully developed, the project team decided to choose QD as the pilot and industrialization base of the project.
In January 2018, with Cheng Huiming as the chief scientist, Dr. Jia and his R&D team jointly developed an industrialized production line.
Quality reaches world-class
After the successful pilot test, the challenges facing industrialization have not diminished. In the industry, even if the equipment of the combustion synthesis method reaches 40 liters, it is the largest. Other Chinese enterprises that have achieved industrialization only copy the 40 liters of equipment to increase production, but this method is costly and not competitive.
QDCX designs and manufactures larger equipment, and must make high-end silicon nitride in the equipment that is gradually increased to achieve competitive industrialization. “At the beginning, we moved forward in small steps. According to the design requirements of the 40-liter reactor, we cooperated with the equipment manufacturer to gradually increase the reactor to 60 liters and then to 150 liters. Because the increase is not too large, although the experimental process has There was a lot of trouble, but finally the experiment was relatively smooth and successful.
However, when the 150-liter equipment surged to 2000 liters, QDCX encountered an unprecedented problem: it could not ignite. After 4 and a half months and spent more than 40 million yuan, the company finally figured out a set of production rules in large-scale equipment and successfully produced high-end silicon nitride products.
The product development is successful, and the production equipment is gradually transformed into fully automated. Now it has realized the computerized intelligent adjustment of the whole production process, relying on precise control, the company has been able to produce cutting-edge silicon nitride powder, and the quality has reached the world-class level.
Today, QDCX has designed the third generation of industrial equipment-4000 liters of silicon nitride reactor.
Climb the peak and take another step
After QDCX high-end silicon nitride powder was produced, the first purchasers turned out to be German and Japanese companies.
In January 2020, a German precision advanced ceramics company took the initiative to find QDCX, purchased some products for testing, and started mass purchase after successful testing.
In June 2020, a Japanese top 500 silicon nitride substrate company also took the initiative to find QDCX to purchase silicon nitride ceramic powder products for testing. After the test was successful, it began to purchase in bulk, and the number of purchases is gradually increasing.
Japanese and German companies are the monopolists of high-end silicon nitride powders in the world. This is the first time that they have purchased silicon nitride powders from a Chinese company. This is beyond our expectation and proves the advanced nature of QDCX products.
At present, QDCX products have been exported to many countries and regions such as Germany, Japan, the United States, Sweden and so on. “
The advent of high-end silicon nitride powder products produced in China has greatly reduced the price of foreign high-end silicon nitride powder in the Chinese market. “In the past, no company in China could make silicon nitride powder for circuit substrates. The price of high-end silicon nitride powder sold to China by Japanese companies was very high, reaching 1.2 million yuan per ton. Now QDCX is the only company in China that can do this. Substrate silicon nitride powder companies have forced Japanese companies to lower the price of high-end silicon nitride powder by nearly 40%.
QDCX’s product quality and cost competitiveness have changed the pattern of China’s high-end silicon nitride powder industry. Many Chinese companies have begun to use QDCX silicon nitride powder, and the number of customers in China has rapidly increased to more than 300 in more than a year.
China`s strongest and largest-scale ZCGX Nitride Ceramic Technology Corporation began to purchase QDCX`s silicon nitride powder products in large quantities after testing QDCX`s silicon nitride powder products in small batches in early 2020, ZCGX Purchasing Manager Jiang Zifei told Hay Think team, they purchase QDCX silicon nitride powder mainly to make silicon nitride ceramic precision structural parts, and now QDCX has become their important supplier.
“Although QDCX has reached world-class levels in terms of alpha phase and impurity content, it still has a gap with the world’s most cutting-edge technology in terms of particle size. This is a natural defect of the preparation method.” Dr. Jia told Hay Think, “QDCX The mission of QDCX is to be the leader of new high-end ceramic materials in China. Although ultra-small particle size is only a necessary option for a few ultra-high-end fields, QDCX still has to work in this direction. The goal is to master all the preparation methods of silicon nitride powder and stand on The world`s top silicon nitride technology.”