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.

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.

电弧离子镀Ti(C_xN_(1-x))薄膜的结构和力学性能研究

利用电弧离子镀设备 ,沉积了不同C、N比的Ti(CxN1 -x)薄膜 ,研究了C含量对Ti(CxN1 -x)薄膜的结构 (相结构、择优取向及晶格常数 )及力学性能 (硬度、膜基结合强度及抗磨损性能 )的影响。结果表明 ,复合镀层的C、N比随CH4、H2 流量之比而变化 ,但原子百分数之和基本不变 (约 4 6.5% )。复合镀层结构致密 ,与基体结合良好 ,抗磨和切削性能优于TiC和TiN镀层。

Al含量对Ti_(1-X)Al_XN涂层组织结构的影响

通过不同 Al含量的 Ti- Al粉末冶金靶 ,采用多弧离子镀技术制备了 Ti1 - XAl XN涂层。用 SEM、 XRD、 GAXRD以及 XTEM等手段研究了 Al元素对涂层组织结构的影响。研究表明 ,Ti Al N涂层呈柱状多晶组织 ,(Ti,Al) N为涂层的主要组成相 ;随着 Al含量的增加 ,涂层中的 (Ti,Al) N相减少 ,且其晶格常数降低。

Ti_(1-x)Al_xN涂层的组织结构及Al元素的作用机理

通过不同Al含量的Ti Al粉末冶金靶 ,采用多弧离子镀技术制备了Ti1 xAlxN涂层 .用SEM、XRD、GAXRD以及XTEM等手段研究了涂层的组织结构及Al元素的作用 .研究表明 ,TiAlN涂层呈柱状多晶组织 ,(Ti,Al)N为涂层的主要组成相 ;随着Al含量的增加 ,涂层中的(Ti,Al)N相将减少 ,且其晶格常数将降低 .

Influence of Si Content on Properties of Ti1-xSixN Coatings

To investigate the evolution of microstructure and wear behavior of TiSiN coatings with the variation of Si in targets and lays the foundation for its controllable mass production, Ti1-xSixN composite coatings were deposited onto Si(100) and cemented carbide substrates using TiSi targets with different Si content by cathodic arc ion plating. The influences of Si on the microstructure and mechanical properties were studied. Nano-amorphous composite structure appeared in the Ti1-xSixN coatings when Si content in TiSi target was higher than 5 at%. However, further increase of Si content in TiSi target exhibited a negligible effect on the microstructure of Ti1-xSixN coatings. Hardness and deformation resistance were correlated to the content of Si in TiSi targets. Maximum hardness was obtained as the Si content in target increased up to 20 at%. Friction coefficient and wear rate significantly decreased with addition of Si in TiN coating, and then dually increased with the increase of Si content in targets.

High temperature oxidation resistance of CrN/(Ti,Al,Zr,Cr)N bilayer films deposited by multi-arc ion plating

CrN/（Ti,Al,Zr,Cr） N bilayer films were successfully deposited on cemented carbide（ WC-8% Co） substrates by multi-arc ion plating process using two Ti-Al-Zr alloy targets and one pure Cr target. As a result of bilayered structure and addition of alloying elements（ e. g. Al and Cr）,the films exhibited excellent high temperature oxidation resistance under both short-term isothermal（ up to 800 ℃） and long-term cyclic（ up to 600 ℃） exposure conditions. Combined with pre-established outstanding tribological properties（ e. g. maximum hardness of 4 000HV0. 01 and maximum adhesion strength over 200 N）,these observations make such films quite a promising candidate to extend the cutting tool life span and boost the performance in high-productivity,high-speed and high-feed cutting or in dry machining conditions.

Oxidation behavior of TiAlZrCr/(Ti,Al,Zr,Cr)N gradient films deposited by multi-arc ion plating

The two Ti-Al-Zr targets and one pure Cr target were used to prepare the TiAlZrCr/（Ti, Al, Zr, Cr）N gradient films on high speed steel （WlSCr4V） substrates by multi-arc ion plating technique. Short-term isothermal （at 600 ℃, 700 ℃, 800℃ and 900 ℃ for 4 h） and long-terra cyclic （at 700℃ and 800℃ for 100 h） high temperature oxidation behavior of the gradient films were studied. Then the oxide scales formed on the film specimens were characterized by scanning electron microscopy （SEM）, energy dispersion X-ray spectroscopy （EDS） and X-ray diffraction （XRD）. It was showed that, under short-term isothermal condition, the high temperature oxidation resistance of the gradient film was excellent up to 800 ℃ and an oxide scale comprising TiO2 was observed. On the other hand, under long-term cyclic high temDerature condition, the oxidation resistance of the gradient film was excellent at about 700 ℃.

耐热钢表面TiAlCrN/NiCrAlY涂层的制备和热震性能

X12CrMoWVNbN10-1-1耐热钢因其优良的性能被用作超超临界蒸汽轮机转子和叶片材料,缺点是随着温度的升高,其性能迅速下降。采用真空电弧离子镀在该耐热钢表面沉积TiAlCrN/NiCrAlY涂层,研究了该涂层的表面形貌、截面形貌、成分和结合力,同时还研究了该涂层在650℃条件下的热震性能。结果表明:使用真空电弧离子镀可制备厚度为8μm的致密TiAlCrN/NiCrAlY涂层,表面成分为Ti0.51Al0.17Cr0.16N0.15。涂层的临界开裂应力LC1为25N,涂层与基体剥离的临界载荷LC2大于60N。通过沉积TiAlCrN/NiCrAlY涂层可显著提高该耐热钢的抗热震性能。

发展中的滴状冷凝强化换热研究

根据“八·五”、“九·五”滴状冷凝课题研究情况 ,介绍BFe30 - 1- 1管表面实现滴状冷凝换热的工艺及其换热试验结果 ,并简介BFe30 - 1-

Effects of honing treatment on AIP-TiN and TiAlN coated end-mill for high speed machining

The objective of this work is to compare the tool performance of TiN and TiA1N coated carbides end-mills deposited by an arc ion plating （ALP） method, using honing treatment to polish the cutting edge surface sleekly. The curve of surface roughness versus honing time showed a rapid improvement initially and thereafter became steady, manifesting a saturation effect. The optimal honing time related to surface roughness was determined to be approximately 20 s. As the surface roughness increased, the critical loads reduced. At an average surface roughness （Ra） of 0.028 p.m, the highest critical loads of TiN and TiAlN coating layers were 98 and 114 N, respectively. Tool performances of uncoated and coated tools were conducted under high speed machining （HSM） of AISI D2 cold-worked die steel （62 HRC）. Consequently, the TiAlN coated end-mill using honing treatment showed excellent tool life under HSM conditions.

Influence of a TiAlN Coating on the Mechanical Properties of a Heat Resistant Steel at Room Temperature and 650℃

A TiA1N coating was deposited on a heat resistant steel X12CrMoWVNbN10-1-1 by vacuum arc ion plating. The tensile and fatigue properties of the coated steel were investigated at room temperature （RT） and 650 ℃. The results reveal that the TiA1N coating is compact, on which a small number of large particle and pits are present. The Ti/Al atomic ratio in the coating is about 0.94. The average hardness of the coating is 1 868 HV0.1 and the interface bonding force between TiAIN coating and the substrate is about 3 l N. The elastic modulus and the strength of the steel are improved by the deposition of TiAIN coating. The influence of the TiA1N coating on the tensile properties of the steel can be ignored at both RT and 650 ℃. Moreover, there is no obvious decrease of the fatigue limit of substrate when the steel is coated by the coating at the investigated temperature.

Combined Effect of Aluminum Content and Layer Structure on the Oxidation Performance of Ti_(1-x)Al_xN Based Coatings

TiN,Ti1-xAIxN single layer coatings and TiN/Ti1-xAIxN multilayer coatings were deposited on SKH51 tool steel substrate by arc ion plating.The coatings were annealed in air to study the effect of aluminum and film structure on the oxidation performance.The surface morphology and structure were characterized by scanning electron microscopy and X-ray diffraction.The element distribution on the cross section was analyzed by electron probe microscopy.It is found that the oxidation resistance of these Ti1-xAlxN based coatings is mainly attributed to aluminum content in them.In comparison with the Ti1-xAlxN single layer coating,the TiN layer inserting into the Ti1-xAlxN in a multilayer coating increases the tendency of Ti diffusion toward the surface and forms a Ti-enriched top surface oxide layer,thus degrades the oxidation resistance.As far as the oxidation resistance is concerned in this study,Ti0.33Al0.67N single layer coating performs the best among all coatings.The kinetic of oxidation behavior of all coatings presents two definite stages.One is a slow oxidation growth which conforms to parabolic law,and the other presents severe mass gain with oxidation duration.The annealing time for severe oxidation initiation is responsible to Fe2O3formation in the oxide scale.

Influence of Negative Bias Voltage on the Mechanical and Tribological Properties of MoS_2/Zr Composite Films

MoS2/Zr composite films were deposited on the cemented carbide YT14 （WC＋14%TiC＋6%Co） by medium-frequency magnetron sputtered and coupled with multi-arc ion plated techniques.The influence of negative bias voltage on the composite film properties,including adhesion strength,micro-hardness,thickness and tribological properties were investigated.The results showed that proper negative bias voltage could significantly improve the mechanical and tribological properties of composite films.The effects of negative bias voltage on film properties were also put forward.The optimal negative bias voltage was -200 V under this experiment conditions.The obtained composite films were dense,the adhesion strength was about 60 N,the thickness was about 2.4 μm,and the micro-hardness was about 9.0 GPa.The friction coefficient and wear rate was 0.12 and 2.1×10-7 cm3/N·m respectively after 60 m sliding operation against hardened steel under a load of 20 N and a sliding speed of 200 rev·min-1.

Improved Electrochemical Performance of Surface-Modified Metal Hydride Electrodes

A novel plating process was applied to the surface modification of the metal hydride （MH） electrode of the MH/Ni batteries. The electrode was plated with a thin nickel film about 0.1 μm thick by using multi-arc ion plating technique. The X-ray diffraction （XRD）, X ray photoelectron spectroscopy （XPS） and scanning electron microscope （SEM） were used to analyze the electrodes. Influence of the surface modification on the performance of the MH/Ni batteries was studied. It is shown that the surface modification could enhance the electrode eondue tivity and decrease the batteries ohimie resistance by 28.2 %. After surface modification, the discharge capacity of the batteries at 5C （8.5 A） is increased by 212 mA· h and discharge voltage is increased by 0.09 V. The surface modification also improves the cyclic durability of the batteries. The inner pressure of the batteries with modified electrode during overcharging is much lower than that with unmodified electrode. The experimental results demonstrate that this process is an effective way for the surface modification of the electrode of MH/Ni batteries.

Low-temperature growth of stoichiometric aluminum nitride films prepared by magnetic-filtered cathodic arc ion plating

A1N films were prepared on Si（100） and quartz glass substrates with high deposition rate of 30 nm-min-I at the temperature of below 85 ℃ by the magnetic-filtered cathodic arc ion plating （FCAIP） method. The as-deposited A1N films show very smooth surface and almost no macrodroplets. The films are in amorphous state, and the formation of A1N is confirmed by Nls and A12p X-ray photoelectron spectroscopy （XPS）. The XPS depth profile analysis shows that oxygen is mainly absorbed on the A1N surface. The A1N film has A1 and N concentrations close to the stoichiometric ratio with a small amount of A1203. The prepared A1N films are highly transparent over the wave- length range of 210-990 nm. The optical transmission spectrum reveals the bandgap of 6.1 eV. The present technique provides a good approach to prepare large-scale A1N films with controlled structure and good optical properties at low temperature.

Preparation of a tantalum-based MoSi_(2)–Mo coating resistant to ultra-high-temperature thermal shock by a new two-step process

To develop an ultra-high-temperature resistant coating for a reusable thermal protection system,the preparation of a tantalum-based MoSi_(2)-Mo coating by a new two-step process of multi-arc ion plating and halide activated pack cementation is presented.The coating has a dense structure and is well compatible with the tantalum substrate,which can be thermally shocked from room temperature to 1750℃ for 360 cycles without failure.The mechanism of the coating’s excellent resistance to high-temperature thermal shocks is that a strong-binding gradient interface and a dense SiO_(2) oxide scale with good oxygen resistance are formed by the high-temperature self-diffusion of Si.