Aichi Science and Technology Foundation
Business Contents
Atom nitridation technology
1. Atom nitriding technology for steel materials
1.1 Principle of nitrogen diffusion layer formation
1.2 Example of atom nitriding
2. Precision mirror-finish cutting of atom-nitrided steel using diamond tools
2.1 Issues with conventional technology
2.2 Developed Technology
2.3 Example of diamond cutting of die steel
1. Atom nitriding technology for steel materials
1.1 Principle of nitrogen diffusion layer formation
In conventional plasma nitriding, the mold or other object is used as the cathode of the glow discharge, and is bombarded with many high-speed ions, resulting in the formation of an iron nitride layer on the mold surface. Therefore, we developed the atom nitriding method, which uses an electron beam to efficiently dissociate nitrogen molecules to generate nitrogen atoms (EBEP: Electron Beam Excited Plasma), which are then used for nitriding. This nitriding method does not require ion bombardment of the mold surface, so iron nitride is not formed. In addition, it has excellent features, such as the ability to appropriately nitride even sharp blades, as it does not require a potential difference between the mold or other object and the plasma.
(Patent No. 2860253, Hara Tamio et al.)
Liu Li, Yamamoto Atsuyuki, Hishida Ryumo, Shoyama Hiroaki, Hara Tamio, Yamanishi Tetsuji, Fukumoto Shinji, Tsubakino Harushige, "Surface microstructure and wear properties of plasma-nitrided AC4C and AC9B aluminum alloys," Light Metals, Vol. 56, No. 10 (2006) pp. 527-532
・Ryūta Ichiki and Tamio Hara, "Electron Beam Excited Plasma Source (EBEP Source)," J. Plasma Fusion Res. Vol.87, No.10 (2011) pp.682-688
・Yasuharu Furukawa, Tamio Hara, Abraha Petros, "Bright nitriding of tool steel using nitrogen plasma," Surface Technology, Vol. 63, No. 2 (2012) pp. 113-117
Atom nitriding equipment schematic diagram
Atom nitriding treatment equipment
1.2 Example of atom nitriding
SEM image of cross-sectional structure after nitriding (Left: Atom nitriding, Right: Plasma nitriding)
Material: SKD61
2. Precision mirror-finish cutting of steel materials using diamond tools
2.1 Issues with conventional technology
There is a high demand for precision cutting of versatile die steels using diamond tools. However, as shown in the figure on the right, there was a problem in that the carbon atoms of single crystal diamond tools diffuse into the iron, causing the cutting edge to wear rapidly.
SEM image of worn diamond tool cutting edge
2.2 Developed Technology
After atom nitriding the surface of high-hardness mold material (e.g. equivalent to high-speed tool steel, HRC63), it is cut with a diamond tool. By machining the nitrogen diffusion layer, which does not generate compounds, we have suppressed the chipping and diffusion wear of the diamond tool and achieved ultra-precise mirror finishing.
(Patent Publication No. 2018-135596, Aichi Knowledge Hub Project Results, Nagoya University Professor Eiji Shamoto et al.)
・Hiroshi Saito, Hongjin Jeong, Eiji Shamoto, Tamio Hara, "Mirror-finish cutting of steel using atom nitriding," Proceedings of the 2017 Japan Society for Precision Engineering Spring Meeting, pp.873-874, N62
Image of the technology developed to suppress the diffusion wear of diamond tools
