Development trend analysis of patent technology of NdFeB permanent magnet material

Neodymium iron boron (NdFeB) permanent magnet material is the third generation of rare earth permanent magnet material, which has a wide range of applications. In this paper, the patent analysis method is used to study the technology development trend of NdFeB permanent magnet materials from the aspects of the overall trend of patent application, production process, grain boundary modification, technical efficacy, regional competition, patent quality and advantageous institutions, so as to provide information support for relevant government departments, enterprises and research institutions to develop the industry and technology of NdFeB permanent magnet materials. The results show that the technology of Nd-Fe-B permanent magnet materials is in a period of rapid development, but there are signs of entering a mature period of technology. Japanese and American applicants have built high patent barriers in this field. In recent years, China’s enthusiasm for research and development of NdFeB permanent magnet material technology is high, and a large number of related patents have been applied. However, from the perspective of patent quality, the technical level needs to be further improved. Finally, the conclusion of the comprehensive analysis provides countermeasures and suggestions for the technological innovation and industrial development of NdFeB in China.

Development status and trend analysis of patent technology of NdFeB permanent magnet

Patent search and analysis method of NdFeB permanent magnet materials

By using Derwent innovation database, combined with keywords, IPC classification and CPC classification, patent retrieval and data collection were carried out. After automatic cleaning and manual cleaning, a total of 7 578 patent families and 19 424 patents related to Nd-Fe-B permanent magnet material technology were obtained, and 3 patents in China were obtained 832, including 2975 Chinese patents applied by Chinese patent applicants (retrieval time range: 1962 to November 2018). Further, the obtained patent data are manually indexed. The indexing words mainly include production process (sintering, bonding, hot pressing), technical efficiency (magnetic properties, high temperature resistance, corrosion resistance, high strength, crack / notch resistance) and subdivision technology (grain boundary modification). Finally, the data after indexing are analyzed by using the tools of DDA, Derwent innovation, incopat and PIAS.

General trend analysis of NdFeB permanent magnet patent

Patent applications for NdFeB permanent magnet materials

According to the number of patent applications and development trend (see Figure 1), the development of NdFeB permanent magnet technology can be divided into three stages: the first stage (1981-1990) and the incubation period. At this stage, patent applicants mainly came from Japan and the United States, and Japan accounted for nearly 90% of the total patent applications. During this period, Sumitomo of Japan and general motors of the United States applied for the patent of Nd-Fe-B permanent magnet material formula respectively, which established their monopoly position in this field for decades. The second stage (1991-2008) is a period of low-speed technology development. In this stage, the number of patent applications showed a certain downward trend, and maintained for a long time. The third stage (from 2009 to now), the period of rapid development of technology. At this stage, China is far ahead in the number of patent applications. It can be said that the substantial increase in the number of patent applications in China directly affects the annual trend of the number of patent applications in this technology field.

Figure.1 annual distribution of patent applications for NdFeB permanent magnet technology
In the 21st century, China’s electronic information, new energy vehicles, wind power generation, household appliances, medical devices and other industries are showing rapid growth in varying degrees, which drives the demand of NdFeB permanent magnet materials, especially high-performance NdFeB permanent magnet materials, which promotes the continuous improvement of technology. Moreover, due to China’s rich rare earth resources and low labor cost, the demand of NdFeB permanent magnet materials is increasing Advantages: the industrial center of NdFeB has gradually transferred to China, and China has developed into a global producer and consumer of NdFeB permanent magnet materials [4, 9, 16]. It can be seen from Figure 2 that during 2012-2017, the number of patent applicants showed a downward trend, indicating that the technology of NdFeB permanent magnet material may be about to enter the mature period of technology, reflecting the fierce competition, higher entry threshold, and small enterprises began to withdraw from the market.

Figure.2 technology life cycle of NdFeB permanent magnet material

Regional competition of NdFeB permanent magnet patent

Dozens of countries and regions have applied for patents in the field of NdFeB permanent magnet technology. As shown in Figure 3, the top countries and regions in patent application are Japan, China, the United States, South Korea and Germany. Among them, Japan has the highest number of patent applications in this field, accounting for 50% of the total number of patents in this field, followed by China, accounting for 39%.

Figure.3 source countries and regions of NdFeB permanent magnet technology patents
Table 1 comprehensively reflects the patent quality of the top 5 countries of origin. China’s patent quality indicators such as the number of patent citations ≥ 5, the average number of citations, h-index and the number of tripartite patents are all behind Japan and the United States. The number of PCT patents is far lower than Japan, but the above indicators are higher than Germany and South Korea, indicating that China has a certain level of patent quality in this technology field, but does not have a leading edge It needs to be further improved.
Table.1 patent quality index of top 5 patent source countries of NdFeB permanent magnet material technology

Table.2 comprehensively reflects the patent quality of the top 10 domestic provinces and cities of NdFeB permanent magnet technology. In terms of the number of patent applications, Zhejiang Province is obviously ahead of other provinces and cities. The h index index is the same as that of Beijing City, ranking first in the same column. However, the indexes of cited ≥ 5 times, average cited frequency are respectively behind Beijing, Liaoning, Shanxi, etc., and the number of PCT patents is behind Beijing and Guangdong It shows that the main body of innovation in Zhejiang Province pays more attention to the protection of intellectual property rights, but the level of R & D needs to be further improved.

Table.2 quality index of top 10 patents of NdFeB permanent magnet material technology

Development trend of NdFeB permanent magnet technology

In order to fully understand the development status of Nd-Fe-B permanent magnet materials technology, we conduct technical indexing of Nd-Fe-B permanent magnet materials, and deeply analyze the indexing content.

Development trend of grain boundary modification technology for NdFeB permanent magnet materials

The main phase of Nd2Fe14B permanent magnet is Nd2Fe14B hard magnetic phase, and the grain boundary phase is nd rich phase. Among them, the composition, structure and distribution of grain boundary phase have a very obvious influence on the magnetic properties, corrosion resistance and mechanical properties of the magnet [17-18]. In recent years, with the rapid development of offshore wind power generation and hybrid electric vehicles, as well as the support of national policies, the demand for high-performance magnets will be increasing, and higher requirements for the heat resistance, corrosion resistance and service life of magnets will be put forward. At present, researchers mainly improve the properties of NdFeB permanent magnet materials through grain boundary modification process [19-22]. The improved technologies mainly include the double alloy method by alloying addition, the grain boundary diffusion by powder mixing non alloy components, and the surface diffusion of magnet to strengthen the grain boundary phase, so as to improve the performance of magnet.
In this study, a large number of patents related to grain boundary modification technology were classified and indexed by manual indexing. The results are shown in Figure 4. It can be seen from Figure 4 that surface diffusion and double alloy method are the main focus technologies of grain boundary modification technology. After 2007, the number of patent applications for several grain boundary modification technologies has increased significantly, indicating that the technology has made new development. The grain boundary modification technology is mainly used to improve the performance of magnets. This phenomenon of patent applications increasing significantly also shows that the market demand for high-performance NdFeB permanent magnet materials drives the improvement of process technology.

Figure.4 annual distribution of patent applications for grain boundary modification technology

Technical efficacy of NdFeB permanent magnet materials

The properties of NdFeB permanent magnet materials mainly include magnetic properties and mechanical properties. The magnetic properties include remanence, maximum magnetic energy product, coercivity, Curie temperature, etc. the mechanical properties include tensile strength, bending strength, hardness, impact toughness, fracture toughness, etc. in addition, the chemical stability (corrosion resistance) [1]. In recent years, with the development of new energy automotive motors, wind power generation, frequency conversion appliances, energy-saving motors and other emerging fields, the demand for high-performance Nd-Fe-B permanent magnet materials is growing, and the research and development of corresponding technical efficiency has become a hot spot. In addition, due to the sharp rise in the price of rare earth metals in recent years, the cost of NdFeB formula has been rising, which has compressed the profit margin. The development of low-cost technology has also become the focus of research and development.
This study analyzes the patent application status of technical efficacy (including magnetic performance, corrosion resistance, high temperature resistance, high strength, crack / notch resistance, low cost, etc.) in the above fields, and the results are shown in Figure 5. It can be seen from Figure 5 that the improvement of magnetic properties is still the main research and development goal of NdFeB permanent magnet materials. Compared with the research and development of special functional materials such as corrosion resistance, high temperature resistance and high strength, low-cost technology is obviously more concerned. In the third development stage of NdFeB permanent magnet materials (from 2009 to now), the number of low-cost technology patent applications began to surpass the corrosion-resistant technology, especially since 2013, the number of patent applications greatly exceeded the corrosion-resistant technology. We analyzed that the reason may be due to a crazy surge in global rare earth prices from 2009 to 2012, resulting in a sharp rise in the cost of raw materials for NdFeB magnets, So that the main body of R & D began to pay more attention to low-cost technology.

Figure.5 annual distribution of patent applications for different technical efficacy

Analysis of patent advantage organization of NdFeB permanent magnet material

There are more than 1500 institutions in the world that have applied for patents in the field of Nd-Fe-B permanent magnet materials, as listed in Table 3. The top 30 institutions are mainly from Japan, China and the United States, mainly Japanese enterprises, with the number of applications far ahead. Hitachi metal, TDK, Datong special steel and Xinyue chemical have been active in the field of NdFeB permanent magnet material technology for more than 30 years. Among the applicants from China, the activity period is less than 20 years, and the proportion of patents applied after 2011 is more than 60%, even more than 90% for two, which shows that Chinese applicants entered the field late and have a high degree of activity in the near future.

Research conclusions and industrial countermeasures

Patent analysis results show that NdFeB permanent magnet materials are in the stage of high-speed technology development, but there are signs of entering the mature stage; Japan and the United States lead the development of NdFeB permanent magnet materials technology, China is a rising star in this field, there is still a gap between R & D and application ability, and the patent quality is low; grain boundary modification technology and other technologies can improve coercivity, improve magnetic energy product and reduce cost The technology for this purpose has received a lot of attention, and the number of patent applications has increased significantly, which has become a research and development hotspot in the near future. The vast majority of leading enterprises have been insisting on the R & D investment in this field, which indicates that this field is still a global R & D hotspot at present and has a good short-term prospect. Nd-Fe-B permanent magnet technology has a high degree of industrialization in China, and enterprises have high enthusiasm to participate.
Based on the technology maturity and life cycle of NdFeB permanent magnetic materials obtained from patent analysis, combined with the actual needs of the development of NdFeB permanent magnetic materials industry in China, the following suggestions are put forward:

• 1) Overall planning, highlighting government guidance. The development of NdFeB permanent magnet industry in China should take high-performance magnets as the goal, take the key technologies such as grain boundary modification, element doping, reduction of rare earth consumption and waste utilization as the breakthrough points, carry out key layout and overall planning, and guide the relevant enterprises to carry out technological breakthrough and breakthrough around the market segments, and develop in the direction of differentiation.
• 2) We will accelerate the research and development of core technologies and promote industrial upgrading and development. It is suggested to establish a technology innovation alliance based on potential enterprises, aiming at the direction of high performance and low cost, and accelerate the research and development of core technology of NdFeB permanent magnet materials. In Beijing, Zhejiang, Jiangxi and other iron boron permanent magnet material industrial parks, we will gather innovative resources, carry out horizontal and vertical integration of the industrial chain, and give full play to the leading role of leading enterprises.
• 3) Promote the industrial chain layout, expand the upstream raw material supply and downstream application market of NdFeB permanent magnet materials. We should attach importance to the supply management of rare earth raw materials, encourage large-scale Nd-Fe-B permanent magnet materials to make full use of their capital advantages, maintain reasonable and sufficient supply and reserve of raw materials, and establish rare earth raw material production enterprises in rare earth resource areas through equity participation or direct plant establishment, so as to ensure stable supply channels and prices of rare earth raw materials. To guide and encourage the application of NdFeB permanent magnet materials in the automotive industry, industrial energy-saving motors, consumer electronics, frequency conversion appliances and other fields.
• 4) Implement patent navigation development strategy and encourage overseas patent layout. This paper analyzes and studies the patent applications of foreign companies in the world, especially in China, formulates the patent protection plan of NdFeB permanent magnet materials, avoids the patent barriers set by foreign companies, constructs the patent protection network in key technology fields, and provides guidance for China to seize the international market of NdFeB permanent magnet materials. We should encourage domestic innovation and overseas patent layout, so as to gradually participate in broader and deeper global competition, and give full play to the role of patents in leading industrial upgrading and development.

Author:ZHANG Fan,SHEN Kai
Source: China Permanent Magnet Manufacturer – www.rizinia.com
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