新型Ti-Si-C-N纳米复合超硬薄膜的高温热稳定性

用脉冲直流等离子体辅助化学气相沉积（PCVD）方法在高速钢基体上沉积出新型Ti—Si—C—N超硬薄膜．Ti—Si—C—N薄膜为纳米晶／非品复合结构（nc—Ti（C,N）／a-Si3N4／a-C—C）,当薄膜中Si和C含量较高时,Ti（C,N）转变为TiC,晶粒尺寸减小到2—4nm．薄膜晶粒尺寸和硬度的高温热稳定性均随沉积态薄膜中的原始晶粒尺寸减小而提高,当原始晶粒尺寸在8—10nm之间时,晶粒尺寸和硬度热稳定性可达900℃;当原始晶粒尺寸在2—4nm之间时,晶粒尺寸和硬度热稳定性可达1000℃．薄膜硬度和晶粒尺寸表现出同步的高温热稳定性．分析认为由调幅分解形成的纳米复合结构中的非晶相强烈地抑制晶界滑移与晶粒长大,从而使Ti—Si—C—N薄膜的热稳定性显著提高．     

Corrosion Behaviour of TiN/a-C Superhard Nanocomposite Coatings Prepared by a Reactive DC Magnetron Sputtering Process

Nanocomposite coatings of TiN/a-C were prepared on tool steel substrates using a multitarget reactive DC magnetron sputtering process at various TiN layer thicknesses (0.6-2.8 nm). The a-C layer thickness was approximately 0.45 nm. Structural characterisation of the coatings was done by X-ray diffraction (XRD). Incorporation of an a-C phase in TiN matrix reduced crystallite size of the coatings, as revealed by XRD and atomic force microscopy. XRD data showed that the nanocomposite coatings exhibited {111} texture and the average crystallite size was ca. 7.5-9.0 nm. Nanoindentation data showed that 1.5 μm thick nanocomposite coatings exhibited a maximum hardness of 5100 kg mm^?2. The potentiody-namic polarisation of 1.5 μm thick coatings in 0.5 M HCl solution indicated that the nanocomposite coalings exhibited superior corrosion protection of the tool steel substrate as compared to the single layer TiN coatings of similar thicknesses. Enhancement in the corrosion behaviour of the nanocomposite coatings has been attributed to small crystallite size and dense microstructure. Potentiodynamic polarisation studies conducted on ca. 100 nm thick nanocomposite coatings revealed that for a given a-C layer thickness the corrosion current decreased with a decrease in TiN layer thickness. This was supported by scanning electron microscopy (SEM) studies on the corroded samples. The SEM micrographs showed that density and diameter of the corrosion pits were smaller for nanocomposite coatings as compared to single layer TiN coatings of similar thicknesses.     

PCVD制备新型Ti-Si-C-N纳米复合超硬薄膜及其微观结构表征

用脉冲直流等离子体增强化学气相沉积（PCVD）方法,在高速钢试样表面沉积出一种新型Ti-Si-C-N薄膜材料.研究了不同SiCl4流量对薄膜成分、微观组织形貌以及薄膜晶体结构的影响.X射线衍射（XRD）、X射线光电子能谱（XPS）、透射电子显微镜（TEM）和扫描电子显微镜（SEM）分析结果表明：Ti-Si-C-N薄膜是由Ti（C,N）/a-C/a-Si3N4组成的纳米复合结构,薄膜的晶粒尺寸在2-25 nm范围内;当Ti-Si-C-N薄膜中N含量很少时,Ti（C,N）结构转变为TiC,薄膜的表面形貌由颗粒状转变为粗条状.     

Dependence of Microstructure and Hardness of Nanocomposite Coatings of nc-(Ti_(1-x)Al_xN)/a-Si_3N_4 on Aluminum Contents

HARD COATINGS are finding a widely applicationin machining industries as tools and moulds since1980s[1].Hard coatings consisting of a variety of thetransition metal nitrides,for instance,TiN,TiC,TiCN,TiBN,TiAlN,CrN etc,usually service as a protectioncoatings that requires some better properties ofwear-resistance,corrosion-resistance and also highfatigue-strength especially at elevated temperature(formore details see Ref.2-6).The generic concept for the design of novelsuper-hard(>40G…     

电沉积方式对Ni-SiC纳米复合镀层性能的影响

目的通过研究电沉积方式对Ni-SiC纳米复合镀层性能的影响,进而改善Ni-SiC纳米复合镀层的性能。方法采用直流电沉积和脉冲电沉积分别制备Ni和Ni-SiC纳米复合镀层,使用扫描电镜和能谱仪研究镀层的表面形貌和成分,通过测量施镀前后镀件质量差计算沉积速率,采用硬度计测量了镀层的硬度,利用极化曲线和电化学阻抗方法研究镀层在3.5%NaCl水溶液中的耐腐蚀性能,分析了直流电沉积方式和脉冲电沉积方式对镀层各项性能的影响。结果脉冲电沉积方式制备的Ni-SiC纳米复合镀层的表面形貌更加致密、均匀、光滑,镀层硬度为616.3HV,自腐蚀电流为9.56×10~(-6) A,比直流电沉积制备的Ni-SiC纳米复合镀层的硬度和耐蚀性能均有所提高。结论电沉积方式对复合镀层的性能有很大影响,脉冲电沉积方式制备的Ni-SiC纳米复合镀层具有更好的性能。     

电磁复合场协同激光熔覆制备TiBw/Ti网状结构复合涂层

目的利用电磁复合场(EMCF)辅助激光熔覆制备TiB_w/Ti网状结构复合涂层,探索电磁场对涂层组织结构的影响。方法以TiB_2∶Ti=1∶1(摩尔比)的混合粉末为熔覆材料,TC4作为基板材料,通过外加电磁复合场进行激光熔覆试验。通过扫描电子显微镜(SEM)观察洛伦兹力方向对熔覆层组织结构的影响,利用X射线衍射仪(XRD)和维氏显微硬度计分析施加电磁复合场前后熔覆层的相组成和硬度分布。结果未施加电磁复合场的熔覆层组织主要为细针状、粗棒状和颗粒状组织。而施加电磁复合场后,熔覆层出现了网状结构,而且方向向下的洛伦兹力可使涂层内部形成空间间距更大的网状结构。此外,单独施加稳态磁场后,熔覆层只出现细针状和粗棒状组织。电磁复合场施加前后熔覆层硬度与基体相比,均有很大的提高。但未施加电磁复合场的熔覆层硬度变化幅度较大;施加电磁复合场后,随着距熔覆层表面距离的增加,硬度的变化幅度比较平缓。结论在洛伦兹力作用下,可得到TiB_w/Ti网状结构的复合涂层,电磁复合场使TiB_w/Ti网状结构强化相均匀分布,同时提高涂层的显微硬度。     

多弧离子镀制备CrAlSiN/TiAlSiN纳米涂层的结构和性能研究

目的研究调制周期对CrAlSiN/TiAlSiN纳米复合涂层结构和力学性能的影响。方法采用多弧离子镀技术,以AlCrSi靶和AlTiSi靶作阴极弧靶材料,通过改变衬底的转速(转速分别为2、4、6、8r/min)来调整涂层结构的周期,制备不同调制周期CrAlSiN/TiAlSiN纳米复合涂层。用X射线衍射仪、X射线光电子能谱仪、扫描电子显微镜和原子力显微镜,测量了涂层的组织结构、化学成分、表面及截面形貌,用显微硬度计、划痕试验仪和摩擦仪测量了不同调制周期的涂层的力学性能。结果不同转速下,CrAlSiN/TiAlSiN纳米复合涂层具有相同的晶相结构,包含CrAl、CrN和TiN,其中Al元素几乎全部固溶在CrAl相中。Si元素在涂层中以非晶相的形式存在或被非晶化合物所包裹。随着转速的增大,复合涂层的硬度呈现先增大后减小的趋势,而摩擦因数与均方根粗糙度则呈现出先减小后增大的趋势,即硬度越大,摩擦因数和均方根粗糙度越小。结论CrAlSiN/TiAlSiN纳米复合涂层的硬度和摩擦因数受调制周期的影响较大。当转速为6r/min时,制备的涂层具有最大的显微硬度(38GPa)和最小的摩擦因数(0.375)。     

Microstructure and mechanical property evaluation of pulsed DC magnetron sputtered Cr–B and Cr–B–N films

CrB₂ and four Cr–B–N films with high Cr/B ratio and various nitrogen contents were deposited by a co-sputtering process using a bipolar asymmetric pulsed DC reactive magnetron sputtering system. The structures and BN bonding nature of the thin films were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), respectively. The surface and cross sectional morphologies of the thin films were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The surface roughness of the thin films was explored by atomic force microscopy (AFM). Nanoindentation, microscratch and ball-on-disk wear techniques were used to evaluate the hardness, and tribological properties of the thin films, respectively.The microstructure of the Cr–B–N thin films changed from a coarse columnar structure to a glassy and featureless morphology as the nitrogen content increased from 15.2 at.% to 54.5 at.%, whereas the corresponding structure developed from an amorphous state to a nanocomposite structure consisting of CrN nanograins and amorphous BN phases. It was found that high hardness, good tribological and brittle properties were obtained for the CrB₂ coating. The hardness and elastic modulus of the Cr–B–N thin films decreased with increasing nitrogen content until the nanocomposite structure of nanocrystalline CrN grains and an amorphous BN matrix was formed. However, the hardening effect induced by the nanocomposite structure was limited due to the fact that the small CrN nanograins were surrounded by a thick intergranular soft amorphous BN layer. On the other hand, the fracture toughness and resistance against elastic strain to failure of the Cr–B–N coatings were effectively enhanced by the addition of nitrogen.     

Effects of Spark-Plasma Sintering Treatment on Cold-Sprayed Copper Coatings

Cold-spray is well known as an effective coating technique to make thick metallic coatings. However, cold-sprayed metallic coatings usually have low tensile strengths due to low adhesion strength between particles, and low ductility due to low adhesion strength between particles and work hardening. Spark-plasma sintering (SPS) is a pressure-sintering technique that employs a large pulsed direct current. Compared to annealing heat treatment (AHT), SPS is expected to effectively improve the adhesion strength between particles in cold-sprayed metallic coatings. In order to investigate the effects of SPS, cold-sprayed Cu coatings were treated by both SPS and AHT under a wide range of temperatures. The microstructures and mechanical properties of the treated specimens were investigated primarily by scanning electron microscopy, electron backscatter diffraction analysis, hardness tests, and tensile tests. Despite comparable values for porosity, crystal grain size, plastic strain distribution, hardness, and yield stress, the tensile strength and ductility of the specimen treated by SPS at 400 °C (SPS400) were significantly higher than those of the specimen treated by AHT at 450 °C. Based on these results, it was determined that SPS treatment is more effective in improving the adhesion strength between the particles in cold-sprayed Cu coatings than AHT.     

Effect of polyaniline–montmorillonite nanocomposite powders addition on corrosion performance of epoxy coatings on Al 5000

A series of polyaniline (PANI)/montmorillonite (MMT) nanocomposite materials has been successfully prepared by in-situ emulsion polymerization in the presence of inorganic nanolayers of clay with camphorsulfonic acid (CSA) and ammonium peroxydisulfate (APS) as surfactant and initiator, respectively. The nanocomposite materials were characterized by Fourier Transformation Infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). Epoxy resin was used as a binder for the nanocomposites in order to obtain a thick and uniform coating. In order to understand the effect of MMT and PANI on the corrosion inhibition performance of the epoxy coatings in 3.5% saline solution at 65 °C, the epoxy (E), epoxy blend with polyaniline (EP), epoxy blend with polyaniline and MMT (EPM) coatings were investigated by electrochemical impedance spectroscopy (EIS). The results showed that EPM coatings with 5% clay on pretreated aluminum by anodizing were much superior in corrosion protection, with respect to the other samples. Incorporation of PACN nanocomposites inside the epoxy significantly increases the resistance of the coating in comparison to the other coatings in 3.5% saline solution at 65 °C. These phenomena can be attributed to specific morphology of the nanocomposite.     

Effect of Ti content on the microstructure and mechanical properties of TiAlSiN nanocomposite coatings

TiAlSiN coatings has been proposed and studied because of their desirable properties in hardness and coating-substrate adhesion. Further improvement of their performance can be achieved by better understanding the effect of the concentration of each element on the microstructure and mechanical properties of the coatings. In this paper, the TiAlSiN coatings with different Ti content were deposited by reactive DC magnetron sputtering method. The microstructure and mechanical properties of the coatings were analyzed by energy dispersive spectroscopy, X-ray diffraction, transmission electron microscope, scanning electron microscope, nano-indentor and Rockwell indentation tester. The results reveal that TiAlSiN coatings consisted of amorphous phase and crystalline phase. With a Ti content of 63 at.%, as well as a Si content of 7 at.%, a super-hard TiAlSiN coating with a nanoindentation hardness of 66 GPa was achieved. What is more, in contrast to the well-described super-hard nanocomposite TiAlSiN coatings, another “nanocomposite” microstructure coating with a Ti content of 29 at.% in which the amorphous phase is wrapped in a crystalline phase was identified, with a comparatively low hardness value of 20 GPa. The highest adhesion strengths with a Rockwell indentation classes HF2 was achieved for a coating with a Ti content of 63 or 65 at.%.     

Influence of bilayer period and thickness ratio on the mechanical and tribological properties of CrSiN/TiAlN multilayer coatings

Nanostructured CrSiN/TiAlN multilayer coatings were deposited by a bipolar asymmetric reactive pulsed DC magnetron sputtering system. The thickness ratio of CrSiN to TiAlN layers was fixed at 1:1. The bilayer periods of the coatings were controlled to be from 6 to 40 nm. Furthermore, two CrSiN/TiAlN multilayer coatings with the same bilayer period (20 nm) but different CrSiN/TiAlN thickness ratios (2:8 and 8:2) were also deposited to explore the influence of thickness ratio on the mechanical properties of the multilayer coatings. The crystalline structures of the coatings were determined by a glancing angle X-ray diffractometer. The microstructures of thin films were examined by a scanning electron microscopy and a transmission electron microscopy, respectively. A nanoindenter, a micro Vickers hardness tester, and a pin-on-disk wear tester were used to evaluate the hardness, the toughness and the tribological properties of the thin films, respectively. The maximum hardness of the multilayers was obtained when the bilayer period was at 10 nm for the coating with the same thickness ratio of CrSiN to TiAlN layers (1:1). Meanwhile, the thickness ratio of CrSiN to TiAlN layer had great influence on the hardness and the toughness properties of the multilayer coatings. The hardness and the toughness of the CrSiN/TiAlN multilayer coatings increased as the individual TiAlN layer thickness increased.     

Mechanical and tribological properties evaluation of cathodic arc deposited CrN/ZrN multilayer coatings

Five nanostructured CrN/ZrN multilayer coatings were deposited periodically by cathodic arc evaporation. The bilayer periods of the CrN/ZrN multilayer coatings were controlled in the range of 5 to 30 nm. The structures and bilayer period of the multilayer coatings were characterized by an X-ray diffractometer. The microstructures of thin films were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. Nanoindentation, scratch tests, Daimler–Benz Rockwell-C (HRC-DB) adhesion tests, microhardness and pin-on-disk wear tests were used to evaluate the hardness, adhesion, indentation toughness and tribological properties of thin films, respectively. It was found that the hardness and tribological properties were strongly influenced by the bilayer period of the CrN/ZrN multilayer coatings. An optimal combination of mechanical properties and excellent tribological behavior was found for a coating with a critical bilayer period of 30 nm.     

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.     

Microstructures and hardness of flat overhead weld of the high strength steel thick plate using double-sided arc welding

High strength steel thick plate is widely used in shipbuilding, pressure vessels, etc., the balance between weld quality and welding efficiency is becoming a research focus. In this paper, double sided double arc flat-overhead welding experiments for high strength steel thick plate were conducted. Microstructures of weld have been observed through optical microscope (OM) and scanning electron microscope (SEM). Transformation of microstructures under thermal cycles of multi peaks was analyzed. Macro and micro hardness were also tested. The results show that the heat-affected zone (HAZ) near the fusion line experiences thermal cycles up to three times. The microstructures there are the most complex, including coarse lath martensite in original coarse-grained zone, and net like structure along grain boundaries in critical reheat coarse grained zone. After several times of tempering for backing welding, the features of acicula and lath are weakened. Its microstructure approaches to the microstructure of base metal which is tempering sorbite. The hardness test shows that the maximum hardness occurs at critical reheat coarse-grained zone, the hardness of reticulation structure at grain boundary can be up to 450HV.     

Effects of cathodic component of current on porosity and hardness characteristics of micro plasma oxidation（MPO） coatings on aluminum alloy

Micro plasma oxidation(MPO) has recently been investigated as a novel, rapid and effective means to provide modified surfaces with improved properties of load bearing and wear resistance on light alloys particularly aluminum alloys. MPO is a muhifactor-controlled process, these factors must be controlled to produce high quality coatings. The main research emphasis in MPO coating development over the past years seems to be the attainment of higher hardness levels and thick coatings. The porosity of MPO coating is the most complex phenomenon affecting the distribution, levels and the measurements of the hardness; and it is controlled by suitable selection of important parameters such as the electrical conditions. Ceramics coatings were synthesized on A1 substrate by MPO to examine the effects of adding a cathodic phase alternated with anodic-cathodic current on the porosity and hardness characteristics of coatings by X-ray diffraction(XRD), scanning electron microscopy(SEM), and microhardness tester. The coatings produced by the combined mode are more dense and less porous than that by the anodic-cathodic mode.Microhardness test shows that the coatings produced by the combined mode exhibit both the highest hardness, and less reduction percentage in hardness with increasing the coatings thickness. These improvements hecome more significant for the polished and thicker coatings.     

新型铝青铜及其喷涂层中Ce元素的作用(英文)

采用一次共装熔炼、砂型铸造Al含量超过Cu-Al二元合金共析点的新型铝青铜合金Cu-14Al-4.5Fe,在45#中碳钢表面制备铝青铜等离子喷涂层。通过扫面电镜、X射线衍射分析、电子探针、透射电镜和显微硬度计分析Ce元素对新型铝青铜合金及喷涂层表面组织形貌和维氏硬度的影响。结果表明:添加0.6%Ce到铸态合金及喷涂层可以使细化的κ相均匀分布于基体,并提高材料硬度。等离子喷涂层快速凝固,保留铝青铜涂层中Fe元素的过饱和固溶体,避免生成(α+γ2)共析相。含Ce喷涂层中的堆垛层错是提高材料力学性能的因素。     

Effect of surfactant on the co-electrodeposition of the nano-sized ceria particle in the nickel matrix

The nickel–ceria (Ni–CeO₂) nanocomposite coatings have been pulse electrodeposited from a Watts-type electrolyte containing nano-sized CeO₂ particles produced by high-energy ball milling technique (HEBM). Sodium Lauryl Sulphate (SLS) has been added in the electrolyte as a cationic surfactant. The effects of the surfactant on the zeta potential, co-deposition and distribution of ceria particles in the nickel matrix and hardness of composite coatings have been investigated. Experimental results show that the addition of SLS up to 0.10 g/l increases the amount of co-deposited ceria particles in the nickel matrix and microhardness of the nanocomposite. However, when the amount of SLS in the electrolyte is more than 0.1 g/l, there is a tendency to form agglomerates of ceria particles in the nickel matrix resulting no further increase in hardness of the Ni–CeO₂ nanocomposite coatings.     

Ion beam assisted deposition of TiN-Ni nanocomposite coatings

Hard and tough nanocomposite coatings consisting of hard TiN nanograins embedded in a soft metallic intergranular phase of Ni have been produced using ion beam assisted deposition. The chemical composition has been obtained by Rutherford Backscattering and the microstructural properties: phases, grain size, and texture of the coatings have been investigated by X-Ray Diffraction. In the composition range 0-22.5 at.% Ni, δ-TiN is the only crystalline phase and Ni appears as an X Ray amorphous phase. The hardness increases up to a maximum of 41 GPa at ~ 7 at.% Ni which corresponds to a TiN crystallite size of ~ 8 nm and a Ni intergranular phase thickness of roughly 1 monolayer. It is shown that the hardness enhancement in TiN-Ni nanocomposite coatings is not correlated with residual stresses, but rather with the intrinsic properties of the nanostructure. An important improvement in wear resistance is obtained for the coatings exhibiting the highest toughness and not the highest hardness. These results show that ion assisted processing is an effective tool for producing dense TiN-Ni nanocomposite coatings and tailoring their structure and mechanical properties.     

Microstructures and tribological properties of PEEK-based nanocomposite coatings incorporating inorganic fullerene-like nanoparticles

The high strength, wear resistance and high operational temperature of polyetheretherketone (PEEK) have attracted increasing interests of this material for tribological applications. The addition of solid lubricant is an effective way to further improve the tribological properties of polymeric materials. In the present work, inorganic fullerene-like tungsten disulfide (IF-WS₂) nanoparticles were incorporated into PEEK coatings with the aim of reducing the coefficient of friction (COF) and improving the wear resistance of the coatings. The microstructures of IF-WS₂/PEEK nanocomposite coatings were characterized using a combination of SEM, XRD and FTIR measurements. The thermal behaviours of the coatings were determined using differential thermal analysis (DTA). Tribological tests had also been carried out to evaluate the friction and wear behaviours of IF-WS₂/PEEK nanocomposite coatings. The results showed that significant improvement can be achieved in the tribological properties of the nanocomposite coatings by incorporating IF-WS₂ nanoparticles.