PRODUCTION METHOD OF WATER ATOMIZATION METAL POWDER

• Main Authors: NAKASEKO MAKOTO, TAKASHITA TAKUYA, MURAKI MINEO, NAKAMURA NAOMICHI
• Format: Patent
• Language: English; Japanese
• Published: 09.02.2017
• Subjects: ALLOYS; BASIC ELECTRIC ELEMENTS; CASTING; CHEMISTRY; ELECTRICITY; FERROUS OR NON-FERROUS ALLOYS; INDUCTANCES; MAGNETS; MAKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; METALLURGY; PERFORMING OPERATIONS; POWDER METALLURGY; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES; TRANSFORMERS; TRANSPORTING; TREATMENT OF ALLOYS OR NON-FERROUS METALS; WORKING METALLIC POWDER

PROBLEM TO BE SOLVED: To provide a production method of water atomization metal powder.SOLUTION: A production method is configured to: jet water to a molten metal stream which flows down; dividing the molten metal stream for making droplets of the molten metal; then start cooling in which secondary cooling jet water is jetted to the droplets of the molten metal, as secondary cooling, in a position where temperature of the droplets of the molten metal is in a range of a coagulation start point to (coagulation start point+30°C) in a midway of falling of the droplets of the molten metal. By the secondary cooling, the divided droplets are coagulated soon, and impact force by the secondary cooling jet water is transmitted to a stream film adhered to a periphery of each droplet, and the stream film is easily broken and removed from each droplet (particle). Therefore cooling speed of metal particles is improved, for forming water atomization metal powders in which an amorphization ratio is improved. Especially, even an Fe-based soft magnetic alloy in which an Fe ratio is high, and which cannot be easily amorphized, can be made water atomization metal powders having the high amorphization ratio.SELECTED DRAWING: Figure 1 【課題】水アトマイズ金属粉末の製造方法を提供する。【解決手段】流下する溶融金属流に水を噴射し、該溶融金属流を分断して溶融金属の液滴とし、該溶融金属の液滴の落下途中で、該溶融金属の液滴の温度が凝固開始点〜（凝固開始点＋30℃）の範囲内の温度である位置で、二次冷却として、溶融金属の液滴に二次冷却噴射水を噴射する冷却を開始する。この二次冷却で、分断された液滴がすぐに凝固し、液滴のまわりに付着した蒸気膜に、二次冷却噴射水による衝撃力が伝達され、容易に破壊され、液滴（粒子）から除去される。これにより、金属粒子の冷却速度が向上し、非晶質化率が向上した水アトマイズ金属粉末とすることができる。とくに非晶質化が難しいといわれていた、Fe比率が高いFe基軟磁性合金についても、高い非晶質化率を有する水アトマイズ金属粉末とすることができる。【選択図】図１