China’s output of iron and copper-based powders has increased continuously in the past few years, with more varieties and improved quality. Despite growing markets, there are operating pressures from rising costs of energy and raw materials that mean optimised technology and production processes are needed to keep the Chinese PM industry developing quickly but in a stable fashion.
Iron powder (including alloyed steel powder) and copper powder (including copper alloyed powder), the main raw materials of the industry, are widely used in such fields as machinery, metallurgy, chemicals and aerospace materials, whose total global consumption has surpassed 1 million tons. As a basic raw material, the output and the quality of iron and steel powders determine the development of the PM industry. The development of the auto industry can be a stimulant and driver for PM industry development. In the USA and Japan, respectively 71 per cent and 89.5 per cent of PM sintered parts are used in the auto industry, while in China at present, only about 41 per cent of PM sintered parts are used in auto and motorcycle industries.

In recent years the national economy of our country has been developing quickly in a stable manner. The development of some main industries such as automobiles (motorcycles), home appliances, metallurgy and chemicals has driven the growth of the PM industry. Rapid development of the basic materials of powder metallurgy - iron-based and copper-based metal powders - was inevitable. Thirty of China’s producers of iron powder are included in the output statistics, although more than a dozen small-scale producers have been excluded. The total output of iron-based powder has hit 225 thousand tons. The annual output of one producer (Laiwu Iron & Steel Group) exceeded 40,000 tons and three producers (Shanxi Yangquan Linli PM Co., Ltd, Wuhan Iron and Steel (Group) Corp and Höganäs AB Shanghai Branch) exceeded 20,000 tons. Another three - Anshan Iron & Steel Group Corporation, Maanshan Iron & Steel Co., Ltd and Liaoning Beipiao Ltd each exceeded 10,000 tons. The incremental output of iron powder comes mainly from the producers with substantial scales of production. In 2005 around 28,000 tons of Chinese iron-based powder were exported, but on the whole, the grades of our exports are not good, and they are mainly exported to Japan. China imported around 25,000 tons of iron powder that are mainly classified as premixed iron powder.
Output of copper-based metal powder is also rising steadily but fluctuations in raw materials’ prices have impacted margin growth.
The total output of electrolytic copper powder produced by only three manufacturers - GRIPM Advanced Materials Co, Ltd, Chongqing Huahao Smelting Co, Ltd and Shanghai Jiuling Smelting Co, Ltd has reached more than 6500 tons. This means that output of copper-based metal powder in China has exceeded that of Japan.

The last three years have seen the biggest-ever investments in the powder metallurgical The investment worth nearly RMB¥ 0.3 billion (approximately $37.5 million) has brought us an incremental output of iron powder of 65 000 tons and steel powder of 2000 tons. This period also saw the rapid development in the Chinese metal powder manufacturing industry’s capacity. According to a preliminary estimate, China now has a production capacity of nearly 300 000 tons of iron-based powder, and nearly 13,000 tons of copper powder and copper-based alloyed powder. Among the bigger producers, Laiwu Iron & Steel Group PM Co Ltd has a production capacity of 80 000 tons of iron-based powder, since its “40 000-ton water atomised iron and steel powder” production line started up. It took an investment of RMB¥ 120 million (approximately $15 million). It also has a production line of 30 000-ton reduced iron powder capacity. Shanxi Yangquan Linli PM Co Ltd’s six tunnel kilns, together with the 5000-ton fined-reduction furnace (acquired from Cremer GmbH) put into production recently have provided a production capacity of over 20 000 tons.
With the renovation of its large tunnel kilns and the production start-up of the 5000-ton fined-reduction furnace introduced from the USA, Wuhan Iron and Steel (Group) Corp PM Co Ltd now has a production capacity of over 20 000 tons of iron powder. PM Co Ltd of Maanshan Iron & Steel Co Ltd now has a production capacity of more than 10 000 tons of iron powder by means of its 160-metre tunnel kiln and two 5000-ton fined-reduction furnaces from Cremer.
The production capacity of water atomised iron powder produced by the Metallurgical Powder Material Plant of Anshan Iron & Steel Co. has nearly hit 20,000 tons, while some other producers like Liaoning Beipiao Ltd, Shanxi Licheng PM Co Ltd and Hebei Gaocheng Iron Powders Plant are expanding their output through technical transformation.
The expansion of electrolytic copper powder production lines of manufacturers like Chongqing Huahao Smelting Co Ltd and GRIPM Advanced Materials Co Ltd, as well as the renovation of their atomised copper powder equipment has increased the production capacity of both electrolytic copper powder and copper alloyed powder.
Further expansion of applications for iron-based and copper-based metal powders is also regarded as one of the driving forces that are boosting output increases.
Production of iron powder used in the soft magnetic materials industry is speeding up and the use of iron powder in some industries such as chemicals and environmental protection is expanding. Experiments in which iron powder is added to flour are under way.
As production of the PM oil-less bearing has shifted and centred on China, demand for copper powder and copper alloyed powder is increasing.
In 2005, of the sales volume of iron and steel powders in China, 134.4 thousand tons accounting for 52.75 per cent of the sales were used for sintered powder metal products. Other purposes include; 18 000 – 20 000 tons for electrodes; 12 000 tons for magnetic materials; 9000 tons for diamond synthesis and diamond tools; 8000 tons for chemicals (for example, titanium dioxide reductant); 8000 tons for metallurgy; 400 tons for spray coating and spray welding powders; and 28 000 tons for export.
In a breakdown of 2005, water atomised iron powder were 61 500 tons, accounting for 27 per cent; reduced iron powder 163 400 tons (including iron scale reduced iron powder at 136 500 tons), accounting for 60 per cent; highly purified magnetite reduced iron powder 27 700 tons, accounting for 12 per cent; electrolytic iron powder 1070 tons; carbonyl iron powder 170 tons.
As for the problems existing in the product structure, compared with the international statistics, reduced iron powder made from highly purified iron ore accounted for 12 per cent, a relatively lower proportion. Apart from anything else, owing to limited ore sources and ore dressing technology, some producers have problems with reduced iron powder made from highly purified iron ore, such as higher content of silicon or sulphur. Compared with that of some foreign manufacturers, our product quality is poorer, and the products haven’t been able to be used singly in the production of high-end structural parts. The output of water atomised iron powder accounts for 27 per cent, also lower than that of foreign counterparts.
Before 2004 the variety structure of copper-based powder produced by China’s top producers of copper-based metal powder was as follows: Electrolytic copper powder, accounted for 75 per cent of the total output of copper-based powder; atomised copper-alloyed powder, accounted for 20 per cent; such powders as oxidation reduced copper powder, lightly-sintered copper alloyed powder and chemically-reduced copper powder accounted for the rump.
In 2005 the output of atomised copper alloyed powder rose a great deal, accounting for nearly 40 per cent of the total output. Electrolytic copper powder dropped proportionately to around 55 per cent. The output of other powders remains at around 5 per cent.
China has mastered the technology of the industrialised production of iron-based metal powder. Diversifying iron-based metal powder products and improving product quality are the top priorities of Chinese producers of iron-based metal powder today. The methods of reduction and atomisation, the traditional means of production of copper-based metal powder, are being perfected in China. The technologies of oxidation-reduction, light sintering and copper-coated iron have ended up at pilot-plant test stage, and the related products are in wide distribution.
China’s product structure of iron and steel powders is changing for the better. With the development trend of sintered powder metal products towards high-density, high-strength and complex shape, the requirements for the performance of iron-based powder are more and more strict. On the one hand, supply of low-grade iron powder exceeds demand and some producers have had to restrict output to avoid overstock. On the other hand, the supply of high-grade reduced iron powder and water atomised iron and steel powders has been falling short of the demand. Customised powders such as mixed powder, pre-alloyed steel powder and diffusion-alloyed steel powder still mainly depend on imports. In 2005, China’s output of water-atomised iron and steel powders was up to 61 500 thousand tons, up 86.9 per cent from that of 2004. Output of reduced iron powder made from highly purified iron ore reached 27 700 tons, up 40.6 per cent from that of 2004, and output of reduced iron powder made from iron scale achieved 136 500 tons, up 20.4 per cent from that of 2004. China’s product structure of iron and steel powders is being slowly modified. The development of high-performance reduced iron powder and water atomised iron and steel powders - represented by reduced iron powder made from highly purified iron ore - is becoming the trend in China’s iron powder industry. Customised powder will become the highlight.
From the point of view of product use, the output of iron and steel powders used for powder metallurgical parts is 134.400 tons, accounting for 59.7 percent of the total. Although the applications for metal powder are constantly enlarging, in a few years of future, the proportion of iron and steel powders used to produce powder metallurgical parts (especially auto parts) will be increasing continuously to the world average of 70-80 per cent.
The manufacture of copper-based metal powder is mainly focused on the properties of the product, such as powder grain size, particle shape, apparent density, and flowability. At the same time, environmental protection, the cost of production and other factors have to be considered. According to figures, 88 per cent of North America’s 22 000 tons of copper-based powder each year is produced by water atomisation plus oxidation-reduction, whereas most of copper-based metal powder made in Japan and China is produced by electrolysis. With the strengthening of environmental emphasis, the pressure for producing copper-based metal powder by electrolysis increases. However it would be inadvisable to increase production capacity of electrolytic copper powder without thought. The development of new methods to produce copper powder, such as the water atomisation plus oxidation-reduction technology, is the trend in the copper-based metal powder industry. Companies such as GRIPM Advanced Materials Co Ltd, Chongqing Huahao Smelting Co Ltd, and Shanghai Jiuling Smelting Co Ltd, are all developing it and some new products have come into the market.
The difference between China’s iron-based and copper-based metal powders and familiar foreign iron powder and copper powder brands lies mainly in the variety and the quality, quite apart from output levels.
The performance uniformity of iron-based metal powder over different batches directly affects product quality for producers of sintered powder metal products. The quality of a single batch of our iron powder is no worse than the quality of that made in Canada or Sweden. But there is a difference in performance between batches if we supply more than two batches continuously. However, there is nearly no difference in properties between batches of the products made in Canada and Sweden, even where they supply tens of batches.
The reason lies mainly in deep research into the batch-blending procedure before the delivery of iron powder and fine adjustments. Control of iron powder performance means the properties between batches of iron powder can be basically consistent. The chemical composition (especially the oxygen content, carbon content and acid insolubles), particle size and particle size composition have also to be strictly controlled during the course of daily production and technological processing.
Well-known iron powder producers have adopted advanced pre-mixing technology to produce their premixed iron powders. These iron powders can be used directly in the PM factory, and because C, Ni, Cu and other elements are dispersed evenly in the powder, the properties of powder metallurgical parts can be improved a great deal. About 90 per cent of the iron powder imported annually by China is premixed iron powder. At present, both Laiwu Iron & Steel Group PM Co Ltd and the Metallurgical Powder Material Plant of Anshan Iron & Steel Co. are researching pre-mixing technology. This technology is one of the key topics to be tackled urgently in the iron powder industry of China.
The Chinese industry has to pay attention to the development pulse of new iron powder product trends in the world. A number of powder products manufactured domestically are short supply, such as warm compaction formed powder, sinter hardened powder, Cr-contained alloyed powder and powder mixed with special agglomerates that allow green compact strength up to 40MPa that can be machined. We should strive for the topic to be brought to the fore by integrating production, education and scientific research to create more new types of iron-based metal powder.
In copper and copper-alloyed powder, we should steadily develop the production scale of the water atomised copper powder produced and increase varieties - such as copper-coated iron powder. In view of the growth in China of such industries as the powder metallurgical oil-less bearing, we need to strengthen research into the product properties and stability. We should note the research into such technologies as copper powder deep-processing, powder milling, polishing, and anti-oxidation to expand usage of copper and copper - alloyed powder.

The Authors
This article was derived from Analysis of the Production status of Ferrous Powder and Copper Powder in China, a paper by Cui Jianmin, Yuan Yong and Ge Liqiang of the PM Association of China Steel Construction Society, and given at PM Asia 2007.