活性屏等离子渗氮技术在高压开关零件上的应用

传统的直流等离子渗氮技术存在一些固有缺点,容易导致几何形状复杂的零件表面产生较多表面缺陷。采用一种新的等离子渗氮技术——活性屏等离子渗氮(ASPN)技术对高压开关领域零件进行处理。结果表明,ASPN技术应用到高压开关零件上,可以获得均匀美观且质量良好的零件表面,同时获得了较高的表面硬度和扩散层深度,零件的耐磨性能和耐蚀性能均被提高。     

活性屏等离子体源渗氮技术原理及应用

活性屏等离子体源渗氮技术是一种先进的渗氮技术,消除了常规直流等离子体渗氮技术的固有缺陷,且可处理聚合物材料及表面附着氧化皮的金属材料.本文介绍了活性屏等离子体源渗氮技术传质机理的研究进展,在改性低合金钢、不锈钢、工具钢、聚合物材料以及抗菌功能材料等方面的最新结果,评述了活性屏等离子体源渗氮技术存在的问题和发展趋势.     

ASPN系列活性屏等离子渗氮炉通过专家技术鉴定

中国热处理行业协会日前在北京主持召开了由江苏丰东热技术股份有限公司、青岛丰东热处理有限公司、青岛科技大学联合研制的"ASPN系列活性屏等离子渗氮炉"技术鉴定会。活性屏等离子渗氮技术有效解决了传统DCPN技术难以克服的问题,促进等离子渗氮工艺的推广应用,可进行混合装料和密     

纯氮气氛活性屏离子渗氮的研究

在纯氮气氛中，利用活性屏离子渗氮(ASPN)技术对38CrMoAl钢进行了离子渗氮处理，并对渗层的组织结构、硬度、深度等进行了分析。结果表明，只有直流辉光放电电压高于800V时，在纯氮气氛中才能进行活性屏离子渗氮处理。通过对等离子放电空间的粒子进行XRD分析发现，放电电压低于800V时，沉积在基材表面的粒子主要是氧化铁(Fe3O4)；放电电压高于800V时，沉积在基材表面的粒子才是能进行活性屏离子渗氮处理的铁的氮化物(ε，γ‘)。     

纯氮气氛下活性屏离子渗氮处理及其影响因素

利用活性屏离子渗氮(ASPN)技术对38CrMoAl钢在纯氮气氛下进行离子渗氮处理,对渗氮层的硬度、深度、组织结构以及收集粒子的形貌、结构等进行了分析研究.结果表明,电压较低时,Fe主要与O结合生成大量的氧化铁而不能进行ASPN处理,氧起主导作用;只有在电压较高、Fe与N的结合能力较强时才主要生成吸附大量活性氮原子的氮化铁进行ASPN处理.     

40Cr钢富氮层快速离子渗氮技术的探索

用活性屏离子渗氮(ASPN)技术对40Cr钢进行快速离子渗氮技术的研究.本项研究是利用氮在奥氏体与铁素体中分别具有不同的溶解度和扩散速度的特性,采用了在共析温度以上短时间溶氮和在共析温度以下长时间扩散渗氮的两种不同的渗氮机制,进行交替渗氮处理.试验结果表明,采用这种新的渗氮工艺不仅可以显著提高渗氮处理中氮在钢中的内扩散速度,而且渗氮层具有较高的硬度.这种快速渗氮工艺可以用"吸收-扩散"渗氮模型进行解释.     

活性屏与工件的距离对40Cr钢活性屏离子渗氮行为的影响

为提高40Cr钢的抗磨及耐蚀性能,用304不锈钢冲孔板制成的活性屏对40Cr钢进行离子渗氮(ASPN)处理,研究了活性屏与工件的距离对渗层组织结构和性能的影响,并与普通直流离子渗氮(DCPN)进行了比较。用光学显微镜(OM)、X射线衍射仪(XRD)、辉光放电光谱仪(GDOES)、显微硬度计、往复摩擦磨损试验机和电化学工作站对渗层组织、相成分、硬度、耐磨及耐腐蚀性能进行分析。结果表明:经不锈钢活性屏离子渗氮处理后,试样表面得到了致密均匀的渗氮层,渗层主要由ε-Fe2-3N、γ′-Fe4N和CrN相组成,且随着试样与活性屏距离从10mm、20mm增加到30mm,对应的渗层厚度从6μm、4.7μm减小到3.5μm。经氮化处理后,40Cr钢的耐磨性和耐腐蚀性都有显著的提高,ASPN处理后试样的耐腐蚀性较DCPN有明显的提高。     

钛合金等离子体表面渗氮改性的研究进展

钛合金具有强度高、耐蚀性好、稳定性好、生物相容性强等特性,在航天航空等行业具有广阔的应用前景,但其硬度低、耐磨性差,使其应用受到了限制。对钛合金进行等离子体表面渗氮强化处理是目前应用较为广泛的技术。本文将对钛合金的直流辉光离子渗氮、活性屏离子渗氮、辅助阴极离子渗氮、空心阴极辅助离子渗氮、激光辅助离子渗氮以及氮离子注入技术等表面等离子体渗氮工艺进行综述。     

离子渗氮新技术的研究现状

为了克服传统离子渗氮的一些固有缺点，近些年来出现一些新的离子渗氮技术，如活性屏离子渗氮、等离子体源离子渗氮、离子注入离子渗氮等，本文简要介绍了这些新技术及其原理、特点，总结了这类技术的共性模型。其中，活性屏离子渗氮技术和等离子体源离子渗氮技术有着明显的设备和工艺优势，可能成为离子渗氮技术的发展方向。     

双相不锈钢等离子表面硬化技术的进展

双相不锈钢兼具奥氏体和铁素体不锈钢的特点，塑性和耐蚀性好，但硬度低，耐磨性差。等离子表面硬化处理能提高双相不锈钢的表面硬度和耐磨性，包括离子渗氮、直流辉光等离子渗氮、活性屏等离子渗氮、空心阴极辅助离子渗氮、等离子沉积薄膜(物理气相沉积、化学气相沉积)、等离子热喷涂、离子注入以及表面复合处理等。     

Active screen plasma nitriding of materials

Abstract

The rapid development and the uptake of plasma nitriding technology into industrial surface engineering have slowed down in recent years. This is attributed to some of the inherent shortcomings of conventional dc plasma technology, for example, difficulties in maintaining a uniform chamber temperature, instability of the plasma and potential surface damage to parts caused by arcing. Efforts in overcoming these problems have led to the development of active screen plasma nitriding (ASPN) technology. This review demonstrates that with all its technological and environmental advantages, ASPN can be used to treat low alloy steels, tool steels, stainless steels and other steels which can conventionally be nitrided with dc plasma technology. In addition, ASPN can be used to treat non-conducting materials such as oxidised steels and polymeric materials which are not suitable for a dc plasma nitriding system. In the longer term, environmental friendly and technologically advanced plasma nitriding will outperform conventional salt bath and gaseous methods. Active screen plasma nitriding is a novel way of possibly achieving the full potential of plasma technology for thermochemical surface engineering.     

Plasma Nitriding of AISI 304 Stainless Steel in Cathodic and Floating Electric Potential: Influence on Morphology,Chemical Characteristics and Tribological Behavior

In direct current plasma nitriding (DCPN), the treated components are subjected to a high cathodic potential, which brings several inherent shortcomings, e.g., damage by arcing and the edging effect. In active screen plasma nitriding (ASPN) processes, the cathodic potential is applied to a metal screen that surrounds the workload, and the component to be treated is placed in a floating potential. Such an electrical configuration allows plasma to be formed on the metal screen surface rather than on the component surface; thus, the shortcomings of the DCPN are eliminated. In this work, the nitrided experiments were performed using a plasma nitriding unit. Two groups of samples were placed on the table in the cathodic and the floating potential, corresponding to the DCPN and ASPN, respectively. The floating samples and table were surrounded by a steel screen. The DCPN and ASPN of the AISI 304 stainless steels are investigated as a function of the electric potential. The samples were characterized using scanning electron microscopy with energy-dispersive x-ray spectroscopy, x-ray diffraction, atomic force microscopy and transmission electron microscope. Dry sliding ball-on-disk wear tests were conducted on the untreated substrate, DCPN and ASPN samples. The results reveal that all nitrided samples successfully produced similar nitrogen-supersaturated S phase layers on their surfaces. This finding also shows the strong impact of the electric potential of the nitriding process on the morphology, chemical characteristics, hardness and tribological behavior of the DCPN and ASPN samples.     

Investigation of nitrogen mass transfer within an industrial plasma nitriding system II: Application of a biased screen

Active screen plasma nitriding (ASPN) was conceived in order to reduce negative effects observed in direct current plasma nitriding arising from the application of bias to the components. The mechanism of nitrogen mass transfer in ASPN is still not fully understood. Here, we compare the microstructure, composition and hardness response of AISI P20 and H13 steels after nitriding. A set of samples was nitrided with sample bias applied directly and another set was nitrided at floating potential under an active screen. Similar nitrogen content and hardness profiles were obtained for the samples treated using a bias and under an active screen separated from the samples by 12 mm. When the sample-screen separation was increased from 12 to 70 mm the hardness response improved. The principle processes occurring during ASPN are proposed based on the experimental results. In ASPN, a flux of energetic nitrogen species is generated by the active screen which, provided that the samples are within the range of the energetic species, bombards the surface of the samples being treated. This flux is critical in establishing a nitrogen potential and a satisfactory response in the components.     

Progress in control of nitriding potential in ASPN process

Abstract

A novel active screen plasma nitriding (ASPN) process provided excellent temperature homogeneity in the load and showed further progress in the control of nitriding potential. In addition to a variation of the nitrogen partial pressure in the process gas commonly used in the conventional plasma nitriding, the applied bias power strongly impacted the nitriding results. In the present work, an application of both methods for the control of nitriding potential in the ASPN process was systematically investigated for a wide range of process parameters to meet the treatment requirements for different types of engineering steel. A two-stage technique based on proper choice of process temperature and required nitriding potential in each stage has been applied in the ASPN process to avoid unnecessary compromises between sufficient thickness of the compound layer, the maximum case hardness and the acceptable nitriding hardness depth.     

Study of the Active Screen Plasma Nitriding

Active screen plasma nitriding (ASPN) is a novel nitriding process, which overcomes many of the practical problems associated with the conventional DC plasma nitriding (DCPN). Experimental results showed that the metallurgical characteristics and hardening effect of 722M24 steel nitrided by ASPN at both floating potential and anodic (zero) potential were similar to those nitrided by DCPN. XRD and high-resolution SEM analysis indicated that iron nitride particles with sizes in sub-micron scale were deposited on the specimen surface in AS plasma nitriding. These indicate that the neutral iron nitride particles, which are sputtered from the active screen and transferred through plasma to specimen surface, are considered to be the dominant nitrogen carder in ASPN. The OES results show that NH could not be a critical species in plasma nitriding.     

Differences in nitrided layer between classic active screen plasma nitriding and active screen plasma nitriding with hemispherical cathodic cage

Abstract

Active screen plasma nitriding (ASPN) is commonly used when regular surface hardening is necessary. The ASPN technique produces a more homogeneous surface coating than direct current plasma nitriding (DCPN) due to different process principles. The term active screen in plasma nitriding refers to a cathodic cage with a defined geometry. The purpose of this work was to study the differences between ASPN using a hemispherical cathodic cage and ASPN using a normal cylindrical cathodic cage. Following some trials using similar parameters, the tests were carried out with three conditions: with DCPN, with a cylindrical cathodic cage in ASPN and with a hemispherical cathodic cage in ASPN. X-ray diffraction and scanning electron microscopy analysis together with energy dispersive spectroscopy were applied to characterise the nitrided layers. The nitrided layers are not the same for each of the conditions used. The ASPN with a hemispherical cathodic cage produced a layer of almost Fe₃N alone, while the other processes gave significant amounts of Fe₄N in the nitrided layer. Scanning electron microscopy analysis showed different surface morphology for each condition.     

Optimization of the ASPN Process to Bright Nitriding of Woodworking Tools Using the Taguchi Approach

The subject of the research is optimization of the parameters of the Active Screen Plasma Nitriding (ASPN) process of high speed steel planing knives used in woodworking. The Taguchi approach was applied for development of the plan of experiments and elaboration of obtained experimental results. The optimized ASPN parameters were: process duration, composition and pressure of the gaseous atmosphere, the substrate BIAS voltage and the substrate temperature. The results of the optimization procedure were verified by the tools’ behavior in the sharpening operation performed in normal industrial conditions. The ASPN technology proved to be extremely suitable for nitriding the woodworking planing tools, which because of their specific geometry, in particular extremely sharp wedge angles, could not be successfully nitrided using conventional direct current plasma nitriding method. The carried out research proved that the values of fracture toughness coefficient K _Ic are in correlation with maximum spalling depths of the cutting edge measured after sharpening, and therefore may be used as a measure of the nitrided planing knives quality. Based on this criterion the optimum parameters of the ASPN process for nitriding high speed planing knives were determined.     

富氮层快速离子渗氮工艺及机理研究

利用正交试验法对活性屏快速离子渗氮工艺参数进行优化,并对正交试验预测的优化工艺参数进行了验证。利用Fick第二扩散定律对快速离子渗氮优化工艺的富氮层进行了氮浓度、氮浓度梯度的计算。试验及计算结果表明,高温渗氮温度、高温渗氮时间和低温渗氮时间对渗层厚度的影响较大,选择合适的参数可以在渗氮时间不变、渗层硬度不降低的前提下显著增加渗层厚度。当富氮层厚度为8μm时,采用快速渗氮技术得到试样内表面与基体之间的氮浓度梯度,为传统渗氮模式的20倍以上。     

高效节能环保渗碳渗氮技术

介绍了四个内容：（1）新型高效、节能、环保渗碳技术,主要包括预抽真空双室多用炉和气氛控制装置,与通常的气体渗碳相比,渗碳速度更快,内氧化、渗碳气体消耗量及 CO2排放量大大减少;（2）控制气氛真空渗碳炉,该炉采用热传导探头和氧探头双探头进行碳势的闭环控制,可实施真空渗碳、气冷、重新加热至850℃淬火的工艺过程,渗层均匀性好,并能有效消除积炭;（3）预抽真空精密控制气氛渗氮炉,该炉采用独特的温度和氮势精确控制系统,可取代QPQ 技术对普通碳钢进行渗氮氧化复合处理,提高其耐磨、耐蚀和疲劳性能;（4）活性屏等离子渗氮技术,其独特之处是,高压直流电源的负极接在真空室内的金属活性屏上,等离子体加热金属屏,由从屏上辐射的热量将工件加热到所需渗氮温度,解决了传统的直流等离子渗氮技术难以克服的工件打弧等问题。