15-5PH不锈钢基体上硬质膜层制备及性能研究

对比不同的表面处理工艺,选择多弧离子镀方法在15-5 PH不锈钢基材表面制备TiN硬质涂层.分析制备工艺对膜层的表面硬度、膜/基结合强度、膜层结构等基本物理性能的影响,进行工艺优化.结果显示在预热温度高于200℃后,TiN膜层结晶效果较好;负偏压达到600V后,膜／基间“伪扩散”层出现,膜／基结合性能明显提高;工作气压升高,膜层表面硬度、膜／基结合力和沉积速率先升高后下降,分别在4.0,3.0和2.5Pa达到峰值.最终获得的TiN硬质膜层表面硬度大于2000HV0.05,膜／基结合力最小临界载荷高于70N.镀膜处理后,工件的各种性能测试均能满足具体使用要求.     

15-5PH不锈钢表面多弧离子镀高结合性能TiN膜层研究

多弧离子镀方法在15-5PH不锈钢材料表面制备结合力、硬度和致密性高的TiN涂层,提高材料表面硬度和抗高温氧化性能。分析结果显示过渡层成分、预热温度、工作气压及负偏压等主要参数对膜层性能影响明显。得到Ti为过渡层时,预热250℃,气压3.0Pa,600V偏压镀膜工艺参数最佳,制备的膜基结合力高于60N,表面硬度>1200HV0.05,膜层表面大液滴密度尺寸最低。膜层表面显微硬度、膜层沉积速率和膜基结合力随工作气压升高不同程度地先升高后降低。     

直流磁控溅射Cr(Al)N薄膜的结构与性能比较研究

采用相同的基底偏压和靶基距离,以N2流量和靶材溅射功率为变量,以热作模具用钢H13和Si片为基底,用直流磁控溅射的方法沉积了CrN和CrAlN膜层.对这2种膜层用SEM测其表面形貌,用X射线衍射测其膜层结构,用M-400-H1测其表面显微硬度,用WS-97划痕仪测其膜层/基体之间的结合强度,用UMT-2摩擦磨损试验机测其表面摩擦磨损性能.在分析溅射变量对2种膜层的影响趋势的同时,也分析了Al元素加入后所获得的CrAlN与CrN在结构、力学性能(硬度和膜/基粘结强度)和摩擦性能上的变化趋势.     

TC4钛合金表面电弧离子镀TiN/CrN纳米多层薄膜研究

用电弧离子镀技术在TC4钛合金基体上通过改变偏压制备了4组TiN/CrN薄膜,对薄膜的表面形貌、厚度、相结构、硬度、膜基结合力和摩擦系数等组织、性能进行了测试表征。结果表明,薄膜是由TiN相和CrN交替叠加构成的纳米多层薄膜,薄膜的调制周期为60 nm,总的厚度约为480 nm。与基体钛合金相比,镀膜后样品的表面性能与偏压幅值密切相关并有显著提高:显微硬度从基体的3 GPa提高到16.5~24.7 GPa;摩擦系数从基体的0.35大幅度降低到0.14~0.17;薄膜与基体结合牢固,膜基临界载荷在60~80N之间。经电弧离子镀TiN/CrN纳米多层薄膜处理后,TC4钛合金可以满足沙粒和尘埃磨损条件下的耐磨性能要求。     

钼薄膜的制备、力学性能和磨损性能

采用直流磁控溅射技术在GCr15轴承钢底材上沉积了钼薄膜。利用XRD，AFM对不同负偏压下沉积的钼薄膜的结构和表面形貌进行了表征；利用纳米压痕仪对薄膜的硬度和膜基结合强度进行了测定；最后利用DF-PM型动静摩擦系数精密测定仪和扫描电镜(SEM)研究了薄膜的硬度、残余模量与负偏压的关系。结果表明：利用直流磁控溅射法制备的钼薄膜的硬度随负偏压的变化存在最大值，另外负偏压还影响薄膜的微结构、粗糙度以及膜基结合力，但负偏压的改变对钼薄膜的摩擦系数影响不大。     

工作气压和基底偏压对ZrB2/A1N纳米多层膜结构和机械性能的影响

利用射频磁控溅射技术在不同工作气压和不同基底偏压条件下在Si(100)基底上设计合成了ZrB2/AIN纳米多层膜.利用X射线衍射、扫描电子显微镜、纳米力学测试系统和表面轮廓仪分析了工作气压和基底偏压对薄膜的微结构和机械性能的影响.结果表明:大部分ZrB2/AlN多层膜的纳米硬度与弹性模量值高于两种个体材料的混合值.当工作气压为0.4Pa,基底偏压为-60V时,制备的薄膜具有最高的硬度(36.8 GPa)、最高的弹性模量(488.7 GPa)和最高的临界载荷(43.6mN).基底偏压的升高和工作气压的降低会使沉积粒子的动能提高,引起薄膜表面原子迁移率提高,导致薄膜的原子密度提高,起到位错钉扎的作用,晶粒尺度也被限制在纳米尺度,这些均对提高薄膜的硬度和抗裂强度起到了作用.     

偏压对活性屏离子渗氮工艺的影响

通过对40C钢进行活性屏离子渗氮处理,研究了在活性屏离子渗氮工艺过程中工件所加的偏压对渗氮层的影响.试验结果表明,在不加偏压或偏压较低的情况下,对距离活性屏较近的工件,其表面有一定厚度的渗氮层形成,硬度提高;而距离活性屏较远的工件,其表面几乎没有渗氮层的形成,但当增大偏压至400～450 V时,工件表面产生弱的辉光放电...     

离子镀技术中基板偏压作用的研究

本文进行了离子镀机理的研究。用俄歇电子谱仪测定了不同工艺的离子镀膜与基板界面的过度层；用急冷忽热试验法评定了不同工艺的离子镀膜与基板间的结合力，用扫描电镜观察了不同离子镀基板偏压的膜层组织形貌。通过实验证明了离子镀中基板偏压有着以下几点重要作用：加基板偏压可以清除基板表面的氧化物污染层，直流二极型离子镀可以使固态不互溶金属组成的膜－基界面形成“伪扩散层”，其膜－基界面结合力比空心阴极离子镀膜－基结合力高；直流二极型离子镀随着基板偏压的提高可以细化膜层织组、消除柱状晶，提高镀层致密度。     

工作气压和基底偏压对ZrB2/AlN纳米多层膜结构和机械性能的影响

利用射频磁控溅射技术在不同工作气压和不同基底偏压条件下在Si(100)基底上设计合成了ZrB2/AlN纳米多层膜。利用X射线衍射、扫描电子显微镜、纳米力学测试系统和表面轮廓仪分析了工作气压和基底偏压对薄膜的微结构和机械性能的影响。结果表明:大部分ZrB2/AlN多层膜的纳米硬度与弹性模量值高于两种个体材料的混合值。当工作气压为0.4Pa,基底偏压为-60 V时,制备的薄膜具有最高的硬度(36.8 GPa)、最高的弹性模量(488.7 GPa)和最高的临界载荷(43.6 mN)。基底偏压的升高和工作气压的降低会使沉积粒子的动能提高,引起薄膜表面原子迁移率提高,导致薄膜的原子密度提高,起到位错钉扎的作用,晶粒尺度也被限制在纳米尺度,这些均对提高薄膜的硬度和抗裂强度起到了作用。     

偏压对中频反应磁控溅射AlN薄膜结构与性能的影响

采用离子束辅助中频反应磁控溅射技术在单晶硅及YG6硬质合金基体上沉积AlN薄膜,利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、显微硬度计、薄膜结合强度划痕试验仪等对薄膜结构及性能进行表征,着重研究了偏压对中频反应溅射沉积AlN薄膜结构和性能的影响.研究结果表明:所制备的AlN薄膜是由AIN相和A(I)相组成的,偏压的增大,有利于薄膜结晶度的提高,AlN沿(100)晶面择优取向增强;同时,随着偏压的增加,所沉积的AlN薄膜致密度和膜/基结合力均显著提高,而膜层沉积速率和膜基复合硬度则呈降低的规律.     

镍基合金基体上离子镀TiN薄膜的制备及性能

在镍基合金Inconel 740H基底上通过多弧离子镀制备Ti N薄膜.控制温度、气体流量、过渡层成分等重要参数,研究其对Ti N薄膜的表面形貌、力学性能以及耐腐蚀性的影响.多弧离子镀沉积过程中,沉积温度分别为200、250、300℃;过渡层成分分别为Al、Cr、Ti;气体流量分别为Ar 5 Sccm∶N240 Sccm,Ar 6 Sccm∶N248 Sccm,Ar 8 Sccm∶N264 Sccm.实验结果表明:在本实验的温度范围内,Ti N薄膜的致密度、结合力以及表面硬度均随着沉积温度的提高而提高;Cr作为过渡层的效果优于Al和Ti,薄膜成分均匀、表面致密,硬度更高,且耐腐蚀性能优异;在Ar、N2流量比一定的情况下,气体流量对Ti N薄膜的表面形貌和力学性能影响不大.本实验的最佳参数是:沉积温度300℃,过渡层成分为Cr,气体流量为Ar 6 Sccm、N248 Sccm.     

用XPS和AFM等方法研究氮化钛薄膜的物理化学特性

采用反应非平衡磁控溅射方法制备了氮化钛(TiN)薄膜,沉积时的衬底偏压的范围从0V到-500 V.实验结果表明:TiN薄膜的物理特性和力学性能随衬底偏压变化,最佳的薄膜硬度与弹性模量在偏压为-100 V时得到.AFM的测量结果显示薄膜的表面形貌和粗糙度随衬底偏压变化有一个非线性的变化趋势,同样的趋势也出现在Ti2p和N1s的芯态能谱上.特定谱峰的强度和位置的变化预示着偏压引起的薄膜成分和化学态的变化,XPS的结果表明:适当的偏压有助于TiN的成键,稳定的化学结构防止了表面的氧化和扩散,抑制了杂质和缺陷的形成,良好的机械特性归于表面形貌的改善.     

液相沉积法制备类金刚石膜的研究

探讨了用液相法在钛合金表面沉积制备类金刚石膜的可能性,研究了沉积膜工艺条件对膜的影响,得出了适宜的沉积条件。结果表明,通过液相法可以沉积制备得到DLC膜,但与沉积条件有着密切的关系。当电压为1600~1850V、温度为60~62℃、电极间距为8~10mm、沉积时间大于36h时,才能在钛合金表面得到完整的DLC绝缘膜。     

基体负偏压对类金刚石涂层结构和性能的影响

采用直流等离子体增强化学气相沉积技术(DC-PECVD),通过控制基体负偏压的变化在YG8硬质合金基体上制备一系列类金刚石涂层。选用扫描电子显微镜、原子力显微镜、拉曼光谱、X射线光电子能谱、粗糙度仪对涂层形貌和结构进行表征测试。同时,利用显微硬度计、划痕测试仪系统地分析涂层的显微硬度和界面结合性能。结果表明:随着负偏压增大,涂层表面形貌逐渐平整光滑、致密,颗粒尺寸减小及数量降低。拉曼光谱表明,涂层具有典型的类金刚石结构,涂层中sp3键含量呈先增大后减小趋势,最大值约67.9%出现在负偏压为1000V左右,负偏压过大导致sp3键含量降低。显微硬度随负偏压变化规律与sp3键基本相符,sp3键含量决定显微硬度值大小。负偏压过大对吸附离子产生反溅射作用导致涂层厚度减小。当负偏压为1100V时,涂层与基体间的界面结合性能最优。     

二钛酸钾纳米薄膜的原位合成及其性能研究

以Ti(n-OC4H9)4和CH3COOK为前驱体,采用溶胶-凝胶法在较低温度下原位合成了高光催化活性的K2Ti2O5纳米薄膜;采用TG-DSC,XRD,Raman光谱和AFM研究了K2Ti2O5薄膜的晶体生长过程;采用电化学方法测量了薄膜的光电响应.结果表明:原料在约259℃发生反应,在低于414℃的固态反应阶段生成K2Ti2O5晶核,在414℃～600℃的结晶阶段制得K2Ti2O5纳米薄膜,薄膜的颗粒表面非常平整,薄膜的晶粒是沿着一个晶面取向生长;薄膜均匀、致密、透明;在空气中紫外光照时,K2Ti2O5薄膜能很有效的降解OTS(C18H37SiCl3)单分子膜(SAMs),光催化活性比溶胶-凝胶法制备的TiO2薄膜高,光激发和光电响应能力也比TiO2薄膜强.     

The Impact of Preheating and Postcooling on Critical-to-Quality Characteristics in Hot-Dip Galvanizing

Hot-dip galvanizing (HDG) is a widely used method for protecting steel against corrosion to ensure structure's life expectancy. The HDG process includes surface preparation, galvanizing, and posttreatment operations where multiple stage parameters are controlled to ensure the optimal utilization of zinc to achieve expected results at minimum cost. In this experimental study, we investigated the influence of preheating temperature and the postcooling methods on critical-to-quality (CTQ) characteristics in HDG at various sample thicknesses. Measured CTQ characteristics included the thickness, hardness, roughness, and microstructure of the coated layers. Obtained results showed that coating thickness decreased as preheating temperature increased and as sample thickness decreased. The selection of the postcooling method impacts largely coating hardness and surface roughness both increased as the thickness of the specimen increased and as the preheating temperature increased. Microstructure analysis of coatings illustrated that there was an increase in the variation of readings as the sample thickness increased and as the preheating temperature decreased. Therefore, HDG parameters must be tuned to account for variations in the thicknesses of galvanized structures to better ensure life expectancy.     

Effects of bias voltage on the microstructure and mechanical properties of (Ti,Al,Cr)N hard films with N-gradient distributions

(Ti,Al,Cr)N hard reactive films were deposited on high speed steel substrates by multi-arc ion plating (MAIP) technology using pure Cr and Ti-50Al(at.%) alloy targets. The partial pressure of N₂ was raised step by step in each deposition process. The surface morphology, the cross-sectional morphology of fracture sample, the surface compositions and the phase structure of the (Ti,Al,Cr)N films were investigated by scanning electronic microscope (SEM) and X-ray diffraction (XRD). The dense columnar microstructure was obtained in all of the (Ti,Al,Cr)N films, though micro-droplets evidently existed on the surface of the films. The micro-hardness of the film surface, the adhesive strength of the film/substrate and the thermal shock resistance were investigated. The results revealed the effects of bias voltage on the composition, phase structure, and mechanical properties. The improved balanced properties of a micro-hardness of about 50 GPa, an adhesive strength larger than 200 N and a thermal shock resistance of 7-8 cycles were reached at a bias voltage of 150 V. The present super-hard (Ti,Al,Cr)N films with N-gradient distribution may be an actual substitution of TiN, (Ti,Al)N, (Ti,Cr)N and single-layer (Ti,Al,Cr)N hard films.     

The influence of titanium nitride sputter deposition temperature on surface-hardened 2.5% silicon iron

Surface-hardened silicon iron (SiFe), with 2.5% Si, was sputter deposited with TiN by a reactive d.c. magnetron sputtering process. In this work we have studied the influence of the substrate temperature on the adhesion, hardness and the chemical composition of the TiN film and the substrate hardened structure during sputtering. Glow discharge optical spectrometry (GDOS) and electron microprobe analysis (EPMA), together with a scratch tester and a Vickers' hardness instrument, were used to study the chemical composition depth profiles, hardness and the critical load C_L at the TiN-substrate interface. The substrate surface hardness drops from 820 to 225 HV after TiN deposition as a result of decarburization of the SiFe surfaces. This drop in hardness level was found for all the substrate deposition temperatures, between 200 and 600 °C. The TiN surface hardness reached a maximum of 2700 HV at a substrate temperature of 300 °C and dropped to 1400 HV for a substrate temperature of 600 °C. At 200 °C substrate temperature the TiN surface hardness is 2100 HV which is considered to be a normal hardness for stoichiometric TiN film. GDOS chemical composition depth profiles show changes in the relative intensities at the interface when the substrate deposition temperature was at 400 and 550 °C for the elements carbon, nitrogen, titanium, silicon and iron. The O:Ti ratio increases from 200 to 300 °C and decreases between 300 and 500 °C. Above 500 °C, O:Ti starts to increase again. EPMA shows that the TiN surface hardness and critical load values reach a maximum when the interface C:Ti ratio is 0.1 at a deposition temperature of about 300 °C.     

Effect of negative bias voltage on mechanical and electrochemical nature in Ti–W–N coatings

Mechanical and electrochemical surface properties of Si (100) and AISI D3 steel substrates-coated Ti–W–N, deposited by r.f. magnetron sputtering process from a binary (50% Ti, 50% W) target in an Ar/N₂ (90%/10%) mixture, have been studied using nanoindentation, Tafel polarization curves and electrochemical impedance spectroscopy (EIS). The crystallinity of the coatings was analyzed via X-ray diffraction (XRD) and the presence of TiN(111), TiN(200), WN₂(107), and W₂N(220) phases were determined. Depth sensing nanoindentation measurements were used to investigate the elasto-plastic behavior of Ti–W–N coatings. Each group of samples was deposited under the same experimental conditions (power supply, Ar/N₂ gas mixture and substrate temperature), except the d.c. negative bias voltage that varied (0, ?50, and ?100 V) in order to study its effect on the mechanical and electrochemical properties of AISI D3 steel coated with Ti–W–N coatings. The measurements showed that the hardness and elastic modulus increase from 19 to 30 GPa and from 320 to 390 GPa, respectively, as a function of the increasing negative bias voltage. Coating track and coating-substrate debonding have been observed with atomic force microscopy (Asylum Research MFP-3D^®) on the indentation sites. Finally, the corrosion resistance of Ti–W–N coatings in 3.5 wt% NaCl solution was obtained from electrochemical measurements in relation to the increase of the negative bias voltage. The obtained results have shown that at the higher negative bias voltage (?100 V), the steel coated with Ti–W–N coatings presented the lower corrosion resistance. The corrosion resistance of Ti–W–N in 3.5 wt% NaCl solution was studied in relation to the increase of the bias voltage.     

Optimization of the Deposition Parameters of DLC Coatings with the IC-PECVD Method

Amorphous carbon film, also known as diamond-like carbon (DLC) film, is a promising material for tribological application. It is noted that properties relevant to tribological application change significantly depending on the method of preparation of these films. These properties are also altered by the composition of the films. In view of this, the purpose of the present study was to determine the optimal values of selected deposition parameters of hydrogenated DLC films on high-speed steel tool substrates with the inductively coupled plasma enhanced chemical vapor deposition (IC-PECVD) method. To optimize the deposition parameters for hydrogenated DLC films, Taguchi's method was used. Deposition parameters (bias voltage, bias frequency, deposition pressure, and gas composition) were optimized with consideration to hardness of the film. Based on the experimental results, the optimal parameter setting are ?50 V, 500 Hz, 4 µbar, and 90:10 for achieving maximum value of hardness. It was found that bias voltage has greater influence on hardness. At the optimum conditions, the conformance run resulted in a hardness value of 1580 KHN. Atomic force microscopy images showed that the DLC films are smooth with an average roughness (Ra) of 1.24 nm on silicon substrate.