Low-Temperature Plasma Nitriding of Mini-/Micro-Tools and Parts by Table-Top System

Abstract

Miniature products and components must be surface treated to improve their wear resistance and corrosion toughness. Among various processes, low-temperature plasma nitriding was employed to harden the outer and inner surfaces of micro-nozzles and to strengthen the micro-springs. A table-top nitriding system was developed even for simultaneous treatment of nozzles and springs. A single AISI316 micro-nozzle was nitrided at 673 K for 7.2 ks to have a surface hardness of 2000 HV0.02 and nitrogen solute content up to 10 mass%. In particular, the inner and outer surfaces of a micro-nozzle outlet were uniformly nitrided. In addition, the surface contact angle increased from 40° for bare stainless steels to 104° only by low-temperature plasma nitriding. A stack of micro-nozzles was simultaneously nitrided for mass production. Micro-springs were also nitrided to improve their stiffness for medical application.

Controlling Nitrogen Dose Amount in Atmospheric-Pressure Plasma Jet Nitriding

“…Plasma nitriding is a surface technology to dope nitrogen atoms into metal surfaces via plasma chemical reactions to improve wear resistance, and fatigue strength, etc., of materials [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Plasma nitriding is now one of the essential surface treatments used in industry, especially in the automobile industry and die/mold fabrication.…”

“…Conventional plasma nitriding uses low-pressure DC (or pulsed DC) plasmas in the abnormal glow discharge mode, where the batch process with a large vacuum furnace meets the purpose of mass production. In addition, a number of low-pressure plasma modes have recently been applied to nitriding treatment, e.g., active screen plasmas [4][5][6], electron cyclotron resonance plasmas [2,7], and radio-frequency plasmas [8], etc.…”

“…For the radical nitriding, one of the low-pressure plasma nitriding methods using NH 3 and H 2 gas, NH radicals are considered to play a key role [12,13]. Besides, some other papers mention the importance of NH radicals for plasma nitriding [8,14]. Moreover, in gas nitriding, NH 3 dissociates on an iron surface to NH 2 , NH 2 dissociates to NH, and NH dissociates to N and H, in order, indicating that the presence of NH is essential for gas nitriding [25].…”

Special Issue on “Micro/Nano Manufacturing”

“…The Special Issue contains 13 papers covering the topics listed above [6][7][8][9][10][11][12][13][14][15][16][17][18]. The treated micro fabrication technologies range from established processes like elliptical vibration cutting to novel process chains such as the formation of nanoparticle arrays by hot embossing and sputtering.…”

Microstructure and Tribological Properties of Self-Lubricating FeS Coating Prepared by Chemical Bath Deposition Coating Technique

“…Improving the wear resistance of gear materials mainly starts from two aspects: one is to improve the surface hardness of the gear material, and the other is to introduce a lubricating medium. For the 2 of 10 first, surface strengthening methods such as carburizing [10,11], nitriding [12,13], carbonitriding [14,15], thermal chromizing [16][17][18], electron beam surface treatment [4,16], electro brush-plating [5], double glow plasma surface alloying [19,20], or deformation induced martensite [21] are commonly used to improve the performance of the steel surface. However, the hard surface accelerates the wear of its counterpart and is ineffective in preventing strain fatigue of the substrate, which results in scuffing failure, especially under boundary lubrication of rubbing-pairs [22].…”