Structure and wear resistance of TiN and TiAlN coatings on AZ91 alloy deposited by multi-arc ion plating

In order to investigate the microstructure of TiN and TiAlN coatings and their effect on the wear resistance of Mg alloy, TiN and TiAlN coatings were deposited on AZ91 magnesium alloy by multi-arc ion plating technology.TiN and Ti70Al30N coatings were prepared on the substrate,respectively,which exhibited dark golden color and compact microstructure.The microstructures of TiN and Ti70Al30N coatings were investigated by X-ray diffractometry(XRD)and scanning electron microscopy(SEM).The micro-hardness and wear resistance of TiN and Ti70Al30N coatings were investigated in comparison with the uncoated AZ91 alloy. The XRD peaks assigned to TiN and TiAlN phases are found.The hardness of TiN coatings is two times as high as that of AZ91 alloy, and Ti70Al30N coating exhibits the highest hardness.The wear resistance of the hard coatings increases obviously as result of their high hardness.

EXPERIMENTAL STUDY ON SUPERFICIAL COAT OF GEARS OF NITRIDED 32Cr2MoV COATED WITH TiN FILM BY MULTI-ARC ION PLATING

After 32CrMoV is selected to manufacture nitrided gears coated with TiN by multi-arc ion plating, all of these uncoated gears and coated gears run in the gearbox under the same initial conditions so as to compare their difference concerning properties and microstructure. Experiment results indicate that tooth surface of the coated-TiN gears does not suffer surface abnormalities in meshed zone. Instead, the gears with nitrided case exhibit an abrasion mark on the meshed zone of tooth surface, which results in more weight loss of nitrided gears. The morphology of the surface suggests TiN film with more than 2 000 HV is so dense and smooth that coated-TiN gears have higher wear resistance compared with the uncoated gears. The microstructure of coated-TiN gears is finer, hardness is higher and its distribution of coated-TiN gears is more reliable than uncoated ones, which makes nitride layer combined with TiN film tightly. Consequently, the wear-resistance of gears has been dramatically promoted.

Structure and Tribological Properties of CrTiAlN Coatings Deposited by Multi-Arc Ion Plating

CrTiAIN coatings were prepared by using a home-made industrial scale multi-arc ion plating system. The coatings were found to be composites of face-center-cubic CrN and TiN. The surface roughness, microhardness, and tribological properties of the films were significantly affected by the nitrogen pressure and dc-pulsed bias voltage applied to the substrate. The CrTiA1N coatings with the smoothest surfaces were obtained at optimum conditions of nitrogen pressure of 5.0 Pa and bias voltage of -200 V. The samples were found to exhibit a hardness of 2900 HV0.05 with an average friction coefficient of 0.16 and wear rate of 1.5× 10^-16 m^3/N.m against cemented carbide.

Wear-resistance and anti-scuffing of multi-arc ion plating molybdenum films

The multi-arc ion plating technology was employed to prepare the molybdenum films with thickness of 3 μm on the AISI 1045 steel. The wear and scuffing tests were carried out on the ball-on-disc tester. AFM and SEM equipped with EDS were adopted to observe and analyze the morphologies and element compositions of surface,cross-section and worn scar of the Mo film. The phase structure was studied by XRD and the bonding strength between Mo film and substrate was measured by scratching tester. The tribological experiments show that the Mo film possesses a good wear-resistance and an excellent anti-scuffing property. The failure mechanism of Mo film under extreme condition is flaking off.

Analysis of High-Cr Cast Iron/Low Carbon Steel Wear-resistant Laminated Composite Plate Prepared by Hot-rolled Symmetrical Billet

This study developed a new technology for preparing high-chromium cast iron(HCCI)/low-carbon steel(LCS)wear-resistant composite plates by hot rolling at a 1050°C and a rolling speed of 0.2 m/s.The effects of different rolling reductions(30%,45%,and 60%)on the microstructure(interface and HCCI layer)and mechanical properties(bonding strength,hardness,and wear resistance)of the composite plate were studied.SEM images showed that when the reduction was increased,no impurities and interlayers were found between the microscopic interfaces after hot rolling,and the bonding interface exhibited a wave-like shape.EDS analysis showed that the Cr element diffusion between two metals after hot rolling was promoted when the reduction was increased,thereby improving the bonding quality under the same rolling temperature and rolling speed.Experiments showed that due to the stress release effect of the LCS of the cladded layer,the macro-slab shape after hot rolling performed well,and the brittle HCCI layer underwent thermoplastic deformation without cracking.Moreover,the increase of rolling reduction improved the bonding quality.As the rolling reduction was increased,the volume fraction of Cr-carbides in the HCCI layer also increased,resulting in an increase of hardness and wear-resistance.

STUDIES OF Cr-O THIN FILNS DEPOSITED BY MULTI-ARC ION PLATING

This paper presents the formation of Cr-O thin films on an iron substrate by multi-arc ion plating, which are intended to be used as a thermal radiation absorbent in electronic vacuum devices. Only oxygen was used as a reaction gas during deposition, the Cr-O thin film, must have high adhesion and low outgassing rate. The scratch test shows that the critical load, for an applicable Cr-O thin film deposited in oxygen atmosphere alone at a pressure of 8×10-1 Pa, was as high as 6kg.

Fatigue Crack Arrest in Mild Steel via Iron Electroplating

In this work, electrochemical plating treatments were applied to ASTM A36 steel specimens to study the efficiency and limitations of this method for arresting fatigue crack propagation. Electroplated iron was deposited onto the crack surfaces using a circuit in which Swedish Iron served as the anode in a solution of Ammonium Iron(II) Sulfate Hexahydrate. The iron ions were driven into fatigue cracks that were formed within ASTM E399 compact tension specimens. This work showed that an iron-plating treatment operated at 20°C can arrest fatigue crack propagation for a significant period of cycles. The propagation re-initiation lives that resulted ranged from 11,000 to 230,000 cycles. As observed in prior work, the propagation re-initiation life correlated strongly to the magnitude of the stress intensity factor range that was applied during cycling. As this stress intensity increased, the propagation re-initiation life decreased. Repeated treatments on the same crack provided extended service lives by as much as 370,000 cycles or 60% of the entire fatigue life of the component. Future work may show that re-application of the treatment, when conducted prior to crack re-initiation, could further extend the service life indefinitely. The Correia crack closure model was modified to provide an empirical expression for predicting the crack re-initiation life of the treated component. Interestingly, highly effective arrest behavior was still observed for cracks that were loaded to stress intensity factors of only 3 - 6 <img src="Edit_f69af9cd-e908-4aef-8ccb-3b1f36e16d08.png" alt="" />during the treatment but then subjected to 20 <img src="Edit_5ddb9cae-23ad-442d-8e6c-63b5e1d99a0f.png" alt="" /> during cyclic loading. Galvanic corrosion of the plated material exposed to simulated seawater was estimated to be 3 mpy. Future work will examine the use of less active plating alloys and the possibility of applying effective treatments into cracks that are in an unloaded state.

Study on the new materials for fiberboard refiner plate of defibrator

Defibrator is a very important machine in the wood industry for producing fiberboard. The refiner plates are the key parts of defibrator that directly act with the wood, and broken easily. The working life of the refiner plates is of significance to the wood industry. It may affect refining quality, production efficiency, and power consumption. In this paper, the abrasion resistance of the refiner plate made of different materials, the stainless steels and high chromium cast irons, were tested and compared. The results showed that abrasion resistance of refiner plate made of high chromium cast irons was better than that of the stainless steel materials. Although the two kinds of materials have the same compositions, their abrasion resistances have ap-parent difference. The main reason is that the material microstructures have very important effects on their performance. The refiner plates made of developed high chromium cast irons don抰 demand the complex heat treatment. This can simplify the producing process, save the cost of production, decrease labor strength, and increase the production efficiency.

天然氢气规模生成的成因类型与成藏特点

目前对全球天然氢气资源的估量十分巨大,寻找天然氢气的规模聚集区有赖于对其形成机理和富集规律的不断认识。通过对国内外典型天然氢气显示的数据统计,系统总结了全球天然氢气规模聚集的成因类型、并分析了天然氢气藏的分布和成藏特征。研究结果表明:①天然氢气的成因复杂多样,主要包括水岩反应、地幔脱氢、水的辐解、岩石破碎、有机质热解以及微生物作用等,其中,水岩反应生氢和地幔脱气生氢在自然界中普遍发生,在各种地质环境中广泛存在,且其生氢速率高、生氢量大,因此是天然氢气规模生成最重要的2种成因类型。②天然氢气藏的赋存环境集中体现于三大地质背景中:板块俯冲带、前寒武纪富铁地层发育区以及裂谷构造系统。③天然氢气藏的盖层条件受多个因素的影响,不仅要考虑盖层本身的封盖能力,还要考虑由于氢活跃的物理化学性质导致盖层机械性能发生的变化,影响其脆性-韧性行为形成新的裂缝而产生氢气的逃逸。④地下微生物利用氢气进行代谢活动、中深层的加氢生烃作用等耗烃作用不利于氢气规模聚集,因此在寻找天然氢气生成有利区时,应该避开氢被大量消耗的区域。⑤天然氢气的生成时间尺度短和易扩散性等因素,使得天然氢气成藏表现出动态成藏的特征,只要氢生成与散失始终处于一种动态平衡,就能够富集成藏。地下水是水岩反应生氢的必要条件,国外发现的很多天然氢气藏都分布在地下水循环较好的地区。

表面改性对铁基非晶合金微波吸收性能的影响

目的旨在调节铁基非晶合金(IAA)粉体复合材料的微波吸收性能。方法先在铁基非晶合金粉体表面采用磁控溅射局部覆盖铝膜,再使用KH560硅烷偶联剂对粉体进行绝缘包覆。通过XRD、SEM和FT-IR分别对粉体进行材料表征,采用VSM和传输反射法分别测试样品的电磁性能。结果镀铝后铁基非晶合金粉体的复介电常数实部εʹ提高了56.1%,复介电常数虚部εʺ提高了132.4%。绝缘包覆后铁基非晶合金粉体的εʹ降低变为铁基非晶合金的32.6%,εʺ变为铁基非晶合金的25.1%。镀铝再包覆KH560的铁基非晶合金粉体的εʹ和εʺ则分别变为铁基非晶合金的43.5%和36.6%,其复介电常数实部和虚部比镀铝后的样品低,比单纯用KH560包覆后的样品高,显示出镀铝可补偿因KH560绝缘包覆而带来的介电损耗能力下降,有利于调节KH560绝缘包覆的粉体材料的电磁性能。结论对铁基非晶合金粉体的绝缘包覆,改善了相应材料的高频吸收性能,但牺牲了其低频吸收性能,为了弥补这个不足,提出在铁基非晶合金粉体表面局部覆盖铝膜,再进行绝缘包覆,期望在绝缘包覆后,粉体仍有较高的介电损耗能力,达到调节材料中低频电磁波吸收能力的目的。样品模拟反射率曲线显示,样品厚度在2~3 mm时,铁基非晶合金/Al/KH560样品最低峰对应频率低于铁基非晶合金/KH560的相应峰位,铁基非晶合金粉体表面镀铝可明显改善其复合材料的低频微波吸收特性。

镀锌板表面翘皮类缺陷产生原因

针对某热镀锌产线出现的3种典型翘皮类缺陷,采用扫描电子显微镜分析了缺陷的表面形貌和基体组织,用能谱仪分析了缺陷表面及截面的成分,进而对缺陷产生的工序进行鉴别。结果表明:1号试样表面存在还原状氧化铁,截面存在氧化铁及大量的氧化圆点,部分翘皮区域存在高温焊合,圆点由铸坯表面缺陷遗传到后道工序引起;2号试样表面存在还原状氧化铁,截面存在氧化铁,部分翘皮区域存在高温焊合,圆点由热轧过程引起;3号试样不存在氧化铁及氧化圆点,翘皮缺陷产生于冷态。

不同陶瓷颗粒表面处理对陶瓷/高铬铸铁复合材料微观界面的影响

采用传统的高铬铸铁制备电厂用磨煤机磨辊、磨盘已无法满足耐磨需求,陶瓷颗粒增强金属基耐磨复合材料成为替代传统耐磨材料的首选。本文研究了镀镍、镀钛表面处理对陶瓷/高铬铸铁复合材料微观界面的影响。结果表明,表面处理后陶瓷与高铬铸铁界面润湿性改善,可获得较好的铸渗效果。镀镍陶瓷颗粒与高铬铸铁复合材料没有明显的中间过渡层,二者之间的结合强度不高,陶瓷与高铬铸铁结合为机械结合。镀钛陶瓷颗粒与高铬铸铁复合材料的界面由于Ti元素的作用发生化学反应,形成明显的中间过渡层,界面结合强度高,陶瓷与高铬铸铁结合为冶金结合。

KDF3滤棒成型机滤条成型装置改进

【目的】解决KDF3滤棒成型机组滤条成型装置设计不合理导致的滤棒圆周标准偏差sd值较大的问题。【方法】设计一种新型长圆弧外折叠板和一种新型直线式无台阶封口烙铁。【结果】应用改进的成型装置后,滤棒圆周标准偏差sd值降低24.3%,滤棒不圆度平均值降低13.2%;改进前后,生产阶段废品持平,变化不明显。【结论】改进的成型装置可为提高KDF3成型机滤棒圆周质量提供支持。

浅谈镀铁电解液对低温镀铁工艺的影响

本文详细介绍了镀铁电解液对低温镀铁工艺的影响,汇总了其基本类性和性能,目的在于解决当前工艺流程繁琐性、经济性等问题,总结注意事项以及电解液维护办法,解决镀层与基体结合强度差、镀层破裂或打卷现象、镀层粗糙存在针孔麻点、镀层出现层状结构等问题。本次研究采用实验分析法,对镀铁电解液配制进行优化调整,采用低碳钢和盐酸配制、氯化亚铁和盐酸直接配制的方式。试验结果显示,前者具有原材料取材方便、经济性高的优势,但溶解铁屑的时间较长;后者具有制备速度快、处理时间短的优势。

420 MPa级热基镀锌钢板表面爆皮的原因分析

420 MPa级热基镀锌钢板表面产生爆皮缺陷。采用扫描电子显微镜、能谱仪和差热分析仪分析了镀锌板表面爆皮的特征和原因。结果表明:实质上爆皮是热轧板表面形成了疏松和分层的氧化铁皮,主要为FeO;该镀锌钢板的抗高温氧化性能不良,在990和1180℃左右的氧化质量增加速率急剧增大,导致钢板爆皮。通过优化粗轧机除鳞水、增加精轧机架间冷却水流量和调整卷取工艺等改进措施,表面发生爆皮的420 MPa级热基镀锌钢板大大减少。

酸洗汽车结构钢表面色差成因探究及工艺优化

针对酸洗汽车结构钢SAPH370表面出现的下表面条带状色差缺陷,通过光学显微镜、扫描电镜分析缺陷热轧基板氧化铁皮结构及酸洗后微观形貌可知,带钢表面粗糙度差异是造成表面色差的直接原因。结合热轧辊表面状态可知,下表面条带状色差缺陷产生的主要原因是精轧工作辊下辊比上辊辊面氧化膜剥落更严重,辊面状态的差异遗传至热轧基板,最终造成酸洗后表面粗糙度差异。通过优化轧制温度、轧辊换辊周期及轧制润滑工艺等,可以有效消除色差缺陷。

热轧高强度薄规格酸洗板轧制稳定性研究

因成分复杂、强度高、规格薄等特点,热轧高强度薄规格酸洗板在轧制过程中稳定性差,易发生头部轧破、带钢跑偏、尾部甩尾等现象,进而导致带钢表面出现明显的辊印降级,甚至发生堆钢事故,造成经济损失。为保证稳定性,通常会采取提高出钢温度的方法,但会导致表面氧化铁皮缺陷降级率升高。基于此,对头尾控制程序进行了优化,将精轧除鳞头部特殊控制,在双排模式下带钢头部采用单排除鳞,在F1咬钢后开启双排模式,提高头部穿带过程的稳定性;开发了F7机架尾部AGC二次大抬起功能,在F6抛钢后F7 AGC以4.6 mm/s速度抬起,降低尾部轧制力,且尾部厚超60μm的距离控制在8 m以内;研究了F1和F2机架间水除鳞时序,将F1-F2机架间水逐步投用,让出带头带尾部分,机架间水的使用将精轧轧制速度提高1~3 m/s,减少尾部温降,提高尾部的轧制稳定性;轧制油投用降低负荷5%;优化轧机负荷分配,F2压下率<50%,明显改善了轧辊剥落现象,辊系氧化铁皮的发生率由0.28%降至0.25%。通过优化生产过程各段参数,提升了热轧高强度薄规格酸洗板的轧制稳定性和表面质量。

低温镀铁技术的发展

简要回顾了低温镀技术及其理论研究的发展及现状，并结合生产实践的要求，提出了该课题今后的研究方向。

全光亮镀铁工艺的研究

介绍了一种新型的电镀光亮铁的工艺 ,使用了“抑氢剂”,并用小槽电镀、Hull Cell实验研究了镀液的性能 .还运用线性电位扫描法、旋转圆盘电极法测试了镀液的阴极极化性能和整平性能 ;采用 SEM法观察镀层的形貌 .实验结果表明 :光亮剂的加入可增大铁沉积时的阴极极化 ,并伴有整平作用 ;而抑氢剂可增大氢在铁上析出的过电位 ,从而可提高铁沉积的电流效率并降低镀层的应力 .

倾斜板长度对过共晶高铬铸铁半固态组织的影响

用倾斜板冷却体法制备过共晶高铬铸铁浆料,研究倾斜板长度对过共晶高铬铸铁半固态组织的影响。结果表明,倾斜板长度能够影响过共晶高铬铸铁半固态组织,板长小于300mm时初生碳化物以形核和定向长大为主;300～900mm时以初生碳化物相互碰撞产生撕裂、折断及尖角熔化而变得细小圆整为主;大于900mm时以初生碳化物合并粘连为主。板长为900mm左右时可得到细小、圆整、弥散分布的初生碳化物组织。