测定未分解氨的简易方法

当采用氨滴乙醉进行气体软氮化时,炉内发生如下反应:2NH_3→2〔C〕 3H_2O,C_2H_5OH→〔C〕 3H_2 CO。和普通氮化一样,炉气的氮势决定于未分解氮和氢的含量。若知道了未分解氨的含量,可为调节氨的流量和乙醇滴入量提供一定的依据,知道了氨分解率则就知未分解氨,因此,氨分解率是气体软氮化中的一个重要工艺参数。在设备较齐全的工厂,一般都配有氨分解率测定仪,但该仪器是玻璃的,易损坏,而且有些地区市面上还难以买到。为了满足生产需要,我们利用疏     

可控氮势氮化炉的不锈钢渗氮

可控氮势,即利用目前世界最先进的氢探头,直接定量测试炉内氢的含量,通过计算机将氢量与氮势的定量数学模型转换为氮势,实现对氮化气氛的监控,确保氮化的高质量和可靠性。 众所周知,不锈钢的氮化有一定困难,必须去除表面的钝化膜,才能保证氮化的正常进行。比较成熟的不锈钢的氮化方法,是在炉内加入一定数量的氯化氨,依靠氯化氨分解反应产生的氯气来清除零件表面的钝化膜,活化零件表面,为正常氮化提供保证。然而,对于我公司所用氮势控制氮化炉,采用加入氯化氨的工艺方法有一定困难,因为氮化氨分解产生的氯气对氢探头会产生一定的腐蚀,直     

防止氮化罐“老化”的方法

不锈钢氮化罐使用一段时间后,氨分解率逐渐增高,为保持一定的氨分解率必须加大流量,严重时甚至无法控制,这就是氮化罐的老化现象。过去一般都采用高温退氮和喷砂来解决,但是当老化现象严重时,这两种办法都不行。后来,我们在氮化罐内涂一层水玻璃加石墨的涂料,可解决氮化罐老化     

气体氮化氨分解率的自动测量

气体氮化氨分解率测定仪的应用,不仅提高了气体氮化的工艺水平,减轻了工人劳动强度,而且还能通过调节执行机构,实现氨分解率的自动控制。为了配合当前机械工业热处理技术改造的需要,北京分析仪器厂已将QRD-11 12型氨分解率测定仪正式投产。──编者随着我国社会主义建设的飞跃发展,机械工业日益广泛采用氨化热处理,以提高机械零件的表面硬度、疲劳强度及抗蚀能力。气体氮化零件中,氨分解率是一项直接关系到氨化层质量的工艺参数,因此它的测定就成为保证氮化质量的一个重要手段。 目前气体氨化氨分解率大都采用三通玻璃容器(图1)来测定(简…     

江苏光英炉业有限公司南京光英工业炉研究所工业炉新产品研制中心——向您提供新型高效渗氮设备

本系列产品系RN系列氮化炉的改进型产品,主要特点有:1、炉盖风机采用独特的多重密封结构,密封更可靠,炉压可达300mm水柱.2、新型综合风扇和导流系统对流更强劲,气氛流向更合理,渗氮层均匀度达±0.07mm.3、增设鼓风快冷系统更有效,缩短生产周期.4.配置经改进的KRN_2-W型微机氮势控制柜,更精确地按设定程序自动进行炉气氮势、氨分解率、温度、时间等参数的控制,记录和屏幕显示.炉内温差可达军标1-2类指标.     

普通钢板做氮化箱

氮化箱就是气体氮化用的容器,过去我厂所用的氮化箱都是用不锈钢板做成的。用一段时间发生触媒,氨分解率高到无法控制的程度,最后只有报废再作新的,给国家造成了严重的浪费,我们在这方面也进行了研究,我们工人同技术员、干部“三结合”大胆地用普通钢板     

氨分解率的非水测定装置

氮化过程中一般用玻璃管分解率测定器来测定炉气的氨分解率,此法是利用氨溶于水,分解气N_2及H_2不溶于水而排开水的体积这一原理进行的。但由于此法易受操作者技术水平与熟练程度的干扰,精度较低。现我们在类似这种装置的前面增设一个指标部分,制成如图所示的运用消色剂的非水测定装置,大大地提高了测量精度。     

普通钢板做氮化箱

氮化箱就是气体氮化用的容器,过去我厂所用的氮化箱都是用不锈钢板做成的。用一段时间发生触媒,氨分解率高到无法控制的程度,最后只有报废再作新的,给国家造成了严重的浪费,我们在这方面也进行了研究,我们工人同技术员、干部“三结合”大胆地用普通钢板卷制氮化箱,卷制完成后,用水玻璃加石墨,进行防护涂料。经过60多炉次的实验证明用普通钢板制造氮化箱,再涂上涂料是完全可行     

氮基气体软氮化新工艺的研究与应用

为了适应引进及出口产品生产的需要,经过大量试验,我们研究成功了以NH_3、N_1、CO_2为介质的氮基气体软氮化新工艺,并应用于生产,取得了明显的技术和经济效益。 1.工艺试验 试验使用的设备是经过改造的18kW和35kW井式气体氮化炉。为控制氨气流量及通入炉内的压力,装有一台氨气控制箱,为测量氨分解率,安装     

热处理经验两则

渗氮罐退氮的简易方法 用Q235制作的渗氮罐在使用一段时间后会出现氨分解率过高,不易控制的现象。为了解决这一问题,《热处理手册)推荐采用高温退氮或刷搪瓷涂料的方法。 我单位前几年自制了一个φ1980～1900mm的大渗氮罐,材质为Q235钢板。刚开始使用时,采用加大通氨量的方法可以控制分解率,维持生产。在使用近10炉后即使加大氨量,分解率也降不下     

氮碳共渗工艺过程中化合物层的形成过程

在RJJ-105井式气体渗氮炉中,对45钢试块进行氮碳共渗,渗剂为氨气和甲醇。结合软氮化的工作原理,通过控制氨气供量、甲醇滴入量和氮碳共渗时间等主要工艺参数,使试块获得不同厚度的表层化合物层,即白亮层。结果表明,在570℃下,当氮势达到一定量以后,随着氮碳共渗时间的延长,白亮层增厚,表层显微硬度增加,但氮碳共渗时间超过4h以上时,随着时间的延长,白亮层厚度无明显变化,但是表面出现明显的疏松,表层显微硬度下降。     

Improving the Properties of Low-Alloy and Carbon Steel Tools by Cyclic Nitriding

Cyclic nitriding characterized by uniform alternation of cycles with high and low nitrogen potential is considered. In the active stage of the process, the surface layer of the steel is saturated with nitrogen, forming a nitride zone. In the passive stage, the nitrides are resorbed and the internal nitriding zone expands. The phase composition of the nitrided layer in У8 and ХВГ tool steels may be regulated so as to increase the wear resistance of the steel and form a smooth hardness gradient over the surface layer. The length of the active and passive stages such that the wear resistance of the steel is 2.5 times greater than in traditional nitriding by ammonia is determined.     

氮势测量和控制技术的研究现状与发展

针对国内外气体渗氮过程中气氛氮势的测量和控制的现状进行了综合评述，认为其发展趋势是深入进行气氛氮势的间接和直接测量专用传感器的研制及实现微机自动控制的可控渗氮。     

The influence of the nitriding process on the dry wear resistance of 15-5 PH stainless steel

The dry wear resistance of 15-5 PH stainless steel nitrided using various methods was investigated. The methods included gas nitriding in cracked ammonia, plasma or ion nitriding and ion implantation of nitrogen. The dry wear resistance and the topography of the wear surface were studied as a function of load and sliding distance. It was found that the wear resistance of the plasma-nitrided specimens is higher than that of the gas-nitrided specimens. The wear resistance of the ion-implanted specimens was even better. However, because of the very small thickness of the implanted layer, only partial results were obtained.     

氨合成塔冷管失效分析

采用金相、电子探针成分分析和显微硬度检测手段研究了断裂冷管段 ,同时进行现场硬度检测 ,说明断裂冷管形成了深度达 1mm的渗氮层 ,且由于渗氮致使氮化层严重脆化和开裂 ,同时氮化层在腐蚀氧化和冷热疲劳作用下 ,导致冷管表面形成了较深的冷热疲劳或氮化脆化裂纹 ,导致冷管的韧性降低 ,甚至断裂。建议严格控制合成塔的操作温度 ,定期检验塔内件承压元件的渗氮程度 ,以确保设备安全运行     

Influence of plasma nitriding on fretting wear behaviour of Ti–6Al–4V

Plasma nitriding was performed on Ti–6Al–4V samples at 520 °C in two environments (pure nitrogen and a mixture of nitrogen and hydrogen in the ratio of 3:1) for two different time periods (4 and 18 h). Fretting wear tests were conducted on unnitrided and nitrided samples for 50,000 cycles using alumina ball counterbody. Plasma nitriding reduced the tangential force coefficient of Ti–6Al–4V. The samples nitrided for 4 h exhibited higher hardness and lower tangential force coefficient compared to the specimens nitrided for 18 h. The samples nitrided in nitrogen–hydrogen mixture environment exhibited higher hardness and lower tangential force coefficient compared to the specimens nitrided in pure nitrogen. The samples plasma nitrided in nitrogen–hydrogen mixture for 4 h exhibited the highest hardness and the lowest tangential force coefficient. The wear volume and specific wear rate of the plasma nitrided samples were lower than those of the unnitrided samples. A consistent trend was not observed regarding which nitriding condition would result in lower wear volume and specific wear rate at different loads.     

Tribological properties of plasma nitrided AISI 4140 steel under dry and lubricated sliding conditions

In this investigation, the microstructural, mechanical and tribological properties of plasma and pulse plasma nitrided AISI 4140 steel have been investigated in comparison to hardened steel. The influence of nitriding case depth, as well as the presence of a compound layer, have been tribologically examined for both dry and lubricated sliding. Testing was carried out on a pin‐on‐disc machine in which surface‐treated pins were mated to hardened ball bearing steel discs. The surface treated samples were characterised using metallographic, SEM, microhardness and profilometric techniques, before and after wear testing. The resulting wear loss and coefficient of friction were monitored as a function of load and of test time. The results showed improved tribological properties of the AISI 4140 steel after plasma and pulse plasma nitriding as compared to the hardened steel, in both dry and lubricated sliding. However, the compound layer should be removed from the surface, either by mechanical means or by decreasing the amount of nitrogen in the nitriding atmosphere, in order to avoid impairment of the tribological properties by fracture of the hard and brittle compound layer, followed by formation of hard abrasive particles.     

微机在渗氮炉、渗碳炉及其机组上的应用

本文从渗氦、渗碳过程的气体反应热力学公式推导出发,找出氦势、碳势控制的原理,寻求优化后的数学模型,采用微机控制系统,开发出微机可控渗氦炉、微机控制碳势箱式多用炉及井式渗碳炉等系列产品,对热处理工艺应用也作了综合介绍.     

离子渗氮气氛对TC4钛合金组织与性能的影响

研究了在不同气氛下进行离子渗氮对TC4钛合金渗氮层的组织与性能的影响。进行了金相组织检查,显微硬度测定,X射线结构分析,磨损试验与渗氮层氧含量测定。试验结果表明,保温时的气氛对控制渗氮层质量有较大的影响     

一种简易液氮汽化装置及其在粉末冶金烧结中的应用

以水浴+空浴方式.采用铝翅片互形管自制了液氮汽化装置,实现液氮汽化;并对由液氮与氨分解供气的烧结气氛系统的应用进行了研究,试图为烧结零件生产企业探索一种简单易行的液氮汽化装置和方法.