低磁不锈钢表面处理工艺及防护涂层体系设计研究

研究了不同表面处理工艺对低磁不锈钢基材自身耐蚀性能及涂层附着性能的影响,通过电化学阻抗及耐阴极剥离性测试确定了适用于低磁不锈钢表面的防护涂层体系。研究结果表明,以棕刚玉为喷砂磨料对基材进行喷砂处理,不仅可以提高基材表面粗糙度,满足涂层高附着需求,同时可降低基材表面残留粒料对基材引起的电化学腐蚀。以环氧锌黄为底层的防护涂层体系,可在不锈钢表面形成一层致密氧化膜,极大限度的阻止膜下扩蚀,使涂层的耐腐蚀性数倍增加。      

湿式微喷砂处理对切削TC4的涂层刀具表面完整性及切削性能影响

采用涂层刀具高速切削TC4(Ti6-Al4-V)时,其寿命短的问题较为突出.对涂层刀具进行表面后处理可大幅提高涂层刀具的表面完整性,是延长刀具寿命的有效途径.针对高速干切削钛合金的TiAlN涂层刀具,选用湿式微喷砂处理工艺进行表面后处理,分析微喷砂处理对涂层刀具表面微观形貌、表面粗糙度、表面显微硬度、表面残余应力的影响规律,并进行高速干切削试验,深入研究微喷砂处理对涂层刀具寿命及磨损机理的影响.结果表明:合适的微喷砂处理工艺(水料混合湿式微喷砂,喷砂压强为0. 1～0. 5 MPa,喷砂时间为0～10 s,喷砂颗粒为Al2 O3 或ZrO2 颗粒)可去除涂层初始表面大颗粒、凸起等缺陷,从而改善刀具的表面形貌,但过高的喷砂参数会在涂层刀面引入凹坑、微裂纹等,增大了其表面粗糙度值.喷砂颗粒、喷砂时间主要影响颗粒撞击涂层表面时对TiAlN涂层材料的去除量,改变涂层刀面的形貌、粗糙度与残余应力,喷砂压强主要影响颗粒的冲击力度,改变表面的硬度与残余压应力.与未处理刀具相比,处理后的涂层刀具的表面完整性提升显著,稳定磨损阶段持续时间延长,刀具寿命可提升50% ,微喷砂表面处理可广泛应用于各种涂层刀具表面处理.     

新型功能陶瓷高效研磨半固着磨具(英文)

为提高功能陶瓷游离磨料研磨效率,减少大颗粒杂质侵入造成的表面损伤,提出了一种高效研磨用的新型半固着磨具(SFAT).分析了SFAT的基本工作机理及其制作过程.通过对典型的功能陶瓷工件硅片的研磨实验,分析了SFAT研磨过程中工件表面质量、加工效率、材料去除形式,以及工艺参数对加工过程的影响.实验结果表明,采用#1000 SiC磨料制作的SFAT研磨后的硅片表面粗糙度在10 min内,从215 nm提高到了30 nm.定义了单位材料去除量内表面粗糙度下降值,作为评价工件精加工表面质量改善效率的指标.实验中,利用SFAT研磨硅片的单位材料去除量内表面粗糙度下降值是相似条件下游离磨料研磨的2倍,这表明利用SFAT加工能够迅速改善工件的表面质量,能够获得比游离磨料加工更高的精加工效率.     

喷砂处理对铝合金性能的影响

表面处理对改善铝合金的物理与力学性能起着至关重要的作用,表面处理方式的选择会对铝合金的性能产生重要的影响。本文借助POLYVAR金相显微镜、JSM-5600型电子显微镜、X射线衍射分析仪等先进测试手段对铝合金试样喷砂处理前后的表面粗糙度、表面微观形貌、表面残余应力及其分布进行了研究,结果表明,喷砂表面处理后,铝合金试样的表面粗糙度明显增加,表面分布的轧制裂纹基本消失,残余应力沿表面均匀分布。     

不同磨料对微晶玻璃化学机械抛光的影响

为了提高微晶玻璃化学机械抛光(CMP)的材料去除速率(MRR),降低其表面粗糙度,利用自制的抛光液对微晶玻璃进行化学机械抛光,研究了4种含不同磨料(Si O2、Al2O3、Fe2O3、Ce O2)的抛光液对微晶玻璃化学机械抛光MRR和表面粗糙度的影响.利用纳米粒度仪检测抛光液中磨料的粒径分布和Zeta电位,利用原子力显微镜观察微晶玻璃抛光前后的表面形貌.实验结果表明,在相同条件下,采用Ce O2作为磨料进行化学机械抛光时可以获得最好的表面质量,抛光后材料的表面粗糙度Ra=0.4 nm,MRR=100.4 nm/min.进一步研究了抛光液中不同质量分数的Ce O2磨料对微晶玻璃化学机械抛光的影响,结果表明,当抛光液中Ce O2质量分数为7%时,最高MRR达到185 nm/min,表面粗糙度Ra=1.9 nm;而当抛光液中Ce O2质量分数为5%时,MRR=100.4 nm/min,表面粗糙度最低Ra=0.4 nm.Ce O2磨料抛光后的微晶玻璃能获得较低表面粗糙度和较高MRR.     

化学机械平坦化材料对蓝宝石抛光速率与粗糙度的影响

采用自主研制的新型碱性蓝宝石抛光液,在蓝宝石化学机械平坦化过程中加入FA/O型非离子表面活性剂,该活性剂能够减小蓝宝石表面粗糙度,同时,在蓝宝石抛光速率下降不明显的情况下实现较高的凹凸去除速率差,有利于实现蓝宝石的全局平坦化。通过实验得到了碱性条件下抛光速率较高、粗糙度较小的最佳pH值。研究了等质量分数等粒径条件下磨料分散度以及抛光温度对抛光速率和蓝宝石表面粗糙度的影响。     

喷砂强化对铝合金薄壁框架件形状的影响及应用

铝合金薄壁框架件铣削加工后会有不同程度的变形,表面喷砂强化既可以提高构件的机械性能,也可以对铣削加工后构件的变形进行矫正,这对构件的变形控制和形状稳定性都具有积极作用.本文针对薄壁件形状特点(壁厚2 mm),分别对构件底部和薄壁进行喷砂处理,并通过X-ray表面应力测试、表面硬度和变形测试,对喷砂后构件的变形状况进行分析.研究发现,改变喷砂粒度、空气压力和表面全喷覆次数,对材料表面应力进行调节,可使铣削加工后构件的变形得以调整,一定条件下,其变形矫直率达85%以上.分析认为,薄壁件形状特点与初始内应力水平使得表面应力在薄壁框架件变形中发挥了主要作用.因而,可以在不同位置采用差异化喷砂工艺,对材料表面应力分布进行针对性调节,使喷砂件的形变达到预期要求,最终通过喷砂表面强化实现对薄壁构件变形的调控.     

基于大型钢铁工件磨料水射流除锈及工艺研究

设计了湿式送料后混合磨料水射流除锈装置,并对装置的主要除锈参数进行了研究。结果表明,喷射压力为40 MPa、磨料量为600 g/min、工件进给速度为2 000 mm/min、靶距为60 mm时,粗糙度R_a为4.51μm,工件表面光滑,满足加工要求。     

固结磨料研磨SiC单晶基片(0001)C面研究

碳化硅(SiC)单晶基片已广泛应用于微电子、光电子等领域.本文针对传统游离磨料研磨加工的缺点,提出了固结磨料研磨SiC单晶基片技术,以前期研究的SiC单晶基片研磨膏配方,试制了一系列固结磨料研磨盘,研究了固结磨料研磨SiC单晶基片(0001)C面时的材料去除率、表面粗糙度及平面度,并与游离磨料研磨进行了对比.结果表明,固结磨料研磨后样品表面有深度较浅的划痕,游离磨料研磨后表面没有划痕,但表面呈凹坑状;游离磨料研磨后工件表面粗糙度轮廓最大高度Rz远大于固结磨料研磨;固结磨料研磨的材料去除率高于游离磨料,固结磨料研磨后的表面粗糙度Ra远低于游离磨料研磨,固结磨料研磨可提高平面度;研究结果可为进一步研究固结磨料化学机械研磨盘、固结磨料研磨工艺参数及机理提供参考依据.     

内衬聚偏二氟乙烯热塑功能层的玻璃纤维复合材料缠绕管弯曲性能测试评价

增强层缠绕角度和聚偏二氟乙烯(PVDF)表面粗糙度是影响内衬PVDF热塑功能层的玻璃纤维复合材料缠绕管弯曲性能的重要因素。采用3种规格的石英砂对PVDF管进行喷砂处理以获得不同的表面粗糙度,以PVDF管为芯模,采用湿法缠绕制作复合材料管。采用四点弯曲测试方法,测试分析如上2种因素对复合材料管弯曲性能的影响。结果表明,PVDF内衬层经过24mesh喷砂处理后,随者缠绕角度的增大,缠绕管的弯曲强度逐渐减小,而曲率半径先增大后减小,其中采用[+45/-45]4缠绕结构的复合材料管曲率半径最小。随喷砂颗粒增大,复合材料管弯曲强度和曲率半径略有增大,弯曲失效后刚度退化趋于缓慢。     

Topography-induced alterations in adhesion structures affect mineralization in human osteoblasts on titanium

The influence of the surface topography of titanium on adhesion proteins like tensin was investigated to reveal a correlation between cellular structures and function in human osteoblasts. We investigated the following pure titanium surfaces: polished, machined, glass blasted, and corundum blasted with R_a values: 0.19, 0.54, 1.22, and 6.07 μm, respectively. Corundum-blasted titanium (CB) as the roughest surface with sharp edges inhibited the formation of fibrillar structures of tensin, impaired the colocalization of tensin and the β1 integrin, and affected the organization of the actin cytoskeleton in MG-63 cells. These effects correlated with a reduced mineralization. We suggest that distinct alterations in adhesion structures due to the surface topography are responsible for differences in cell signaling, which lead to changes in the cellular function like mineralization.     

Influence of acid-etching after grit-blasted on osseointegration of titanium dental implants: in vitro and in vivo studies

Rough implant surfaces have shown improved osseointegration rates. In a majority of dental implants, the microrough surfaces are obtained by grit blasting and/or acid-etching. The aim of this contribution was to evaluate the effects of acid-etching, after the grit-blasted treatment in titanium dental implants, on surface wettability, surface energy, osteoblast responses and its osseointegration behavior. Four surfaces were studied: as-machined, acid-etched, micro-rough by grit-blasting and the combination grit-blasted surface with acid-etched. The surfaces with increasing roughness show more osteoblastic adhered cells. This effect was most pronounced on samples blasted and blasted with acid-etching. The roughness obtained by grit-blasting is the main factor in comparison with the acid etching treatment in the biological response. These results were confirmed in vivo tests and histological analysis. The results demonstrated that the combination of the grit-blasted and acid-etched accelerated lightly bone regeneration at the different periods of implantation in comparison with the grit-blasted implants.     

Morphological and animal study of titanium dental implant surface induced by blasting and high intensity pulsed Nd-glass laser

Machined dental implants of titanium were blasted with Al₂O₃ powder of 250 μm particle size. The surface was irradiated in vacuum with a Nd-glass pulsed laser at 1–3 J pulse energies. The morphology of these surfaces was investigated by optical and scanning electron microscopy. The low intensity laser treatment resulted in some new irregularities but we can observe the blasted elements and caves from the original blasted surface too. The blasted elements were washed out and a new surface morphology was induced by the high intensity laser treatment.The osseointegration was determined by measuring the removal torque in the rabbit experiments. The results were referred to the as machined surface. The blasting slightly increased the removal torque. The laser irradiation increased the removal torque significantly, more by a factor of 1.5 compared to the reference at high laser intensity. This shows the influence of the surface morphology on the osseointegration.The combination of the blasting with the laser irradiation is considered a method to determine the morphology optimal for the osseointegration because the pulsed laser irradiation caused modifications of the micrometer sized surface elements and decreases possible surface contamination.     

Effect of abrasives on the glossiness and reflectance of anodized aluminum alloys

Blasting can eliminate or change the surface texture of as-rolled aluminum alloy by indentation to roughen the alloy’s surface. We investigated the effects of the blasting conditions on the glossiness and reflectance of Al1050-H16 and Al5052-H32 alloys in this study. As-rolled sheets were blasted at various pressures, and then removed for sequential cleaning, chemical polishing, and anodizing steps. After each step the samples were measured by micro-TRI-gloss meter and spectrophotometer to compare the effects produced by the abrasive powders and processing variables. Polyhedral alumina and round iron powders were used as the blasting media. The glossiness (Gs(60°)) decreased as the root mean square roughness (Rq) increased, regardless of the shape of the abrasive powders. The abrasives powders could cause wear and/or fracturing during the blasting process as well as fine debris, which could become embedded in the blasted surface. When an aluminum alloy was blasted with iron powders, the glossiness value after alkaline etching and chemical polishing was greater than that after being blasted with alumina; while the anodized Al5052-H32 alloy’s surface became more yellowish in color.     

Reverse reconstruction of surface topography from residual stress after chip-forming machining of the material

Residual stress is induced in the sample of a material stressed by external forces (tension, pressure, thermal stress, etc.) from the beginning of the stress. An instantaneous level is a function of the intensity of the external deformation work, the time and speed of the deformation, and the degree of immediate surface and volume deformation. It is proportional to the individual deformation limits, i. e., the elastic limit, yield point, flexural strength and breach limit; the maximum is reached at the level of the breach limit. Furthermore, it is dependent on the physical-mechanical properties of the material and on the method, i. e., the technology of straining, or machining. The same applies to the roughness distribution and other topographical features on the machined surface. The tension that has not been exhausted is partly returned to the volume of the sample and partly acts in contact with space, within a certain distance and time. This paper aims to present a reverse reconstruction of the surface topography from residual stresses after chip-forming machining of the material. Our original approach to the solution fully exploits the rules of roughness distribution and other topographic features of the surfaces of the given materials after machining, not only by chip-forming machining.     

Influence of graphite powder mixed EDM on the surface integrity characteristics of Inconel 625

Surface integrity in electric discharge machining (EDM) has always been a major concern in the manufacturing industry. Although, EDM with a powder suspended dielectric has shown good potential in enhancing the material removal rate and improving surface finish, influence of the same on the overall surface integrity is not very clear. The current work utilized the graphite powder and evaluated its role in combination with concentration and machining parameters, on surface roughness (Ra), surface crack density (SCD), white layer thickness, microhardness depth profile, possible phase changes, and residual stress during powder-mixed EDM (PMEDM) of Inconel 625 (a nickel-based super alloy), that is now-a-days regularly used in aerospace, chemical and marine industries. The results showed that significant reduction in surface roughness, crack density, and white layer thickness is possible with the PMEDM process. It also promoted formation of carbides and other alloy compounds which is responsible for augmentation of hardness in surface and subsurface region. The added particles also caused a decline in tensile residual stress of the machined samples.     

Electrochemical characterization of titanium biomaterials using the Mini-cell System

The aim of this work was the electrochemical characterization of modified Titanium surfaces for implants with help of the Mini-cell System (MCS). The materials tested were Cp titanium specimens, designed for animal experiments, with 8 mm length and 4 mm diameter, with different surface conditions: one had machined surface, the other was blasted with a bioceramic (GB14+AP40) and the third was blasted with aluminum oxide. Roughness measurements were also made on the materials. The results showed that MCS has sensitivity to detect differences in the electrochemical point of view due to surface modifications. The differences between the materials are small, but systematic. The aluminum oxide blasted material had the highest current density, however due to the roughness increase. The material with bioceramics blasting had the highest chemical activity. The higher activity of the bioceramics treated surface was explained as (i) an interaction between the modified surface and electrolyte; or (ii) the calcium phosphate dissolves in the electrolyte and leaves the surface of the metal, and then the free metal reacts immediately to form new titanium oxide. These results may help to explain the biological effects observed by modified surfaces, in particular with bioceramics.     

Passivation layer effect on surface integrity induced by Cu-CMP

To achieve efficient Cu-Chemical-Mechanical Polishing planarization at miniaturized device dimensions, there is a need for a better understanding of the surface integrity induced by the process. Surface quality and stresses are the two selected indices in this article to evaluate the Cu-CMP process induced surface integrity. The thickness of the passivation layer and the penetration depth of abrasives are considered as the main effects for the generations of surface qualities and residual stress. Experimental validation on copper films on silicon wafer was performed by CMP with different pads and slurries to generate varied residual stresses and surface qualities. Depth of scratches and surface roughness were measured by the atomic force microscope. The stress measurements of the thin films were performed by a Grazing Incident X-ray diffraction instrument with its principles based upon modified sin²Ψ method. Accordingly, the surface roughness and stress were related to the thickness of the passivation layer and the CMP process conditions. When the penetration depth is larger than the passivation layer thickness, the roughness values are mainly decided by the selection of pads and the resultant penetration depth. In addition, the residual stress profiles are dependent on the CMP process conditions which include the slurries and pad parameters. The stress profile obtained for the slurry SDK with soft pad Politex composed smallest maximum tensile stress below the surface and a steady transition of stress profile compared to the stress profile obtained at the initial condition. At the condition for the same slurry SDK, but with a hard pad of IC1000, the CMP process induced larger maximum stress and sharper profile transition.     

High cycle fatigue life estimation of materials processed by laser powder bed fusion

The fatigue life of metal components is known to depend on the surface topography. For components made by laser powder bed fusion, the roughness of the as‐built surfaces depends on the orientation of the component surface with respect to the build plate. Surface topographies of AlSi10Mg and Inconel 718 specimens built at 0° to 90° inclination, with 15° increments, were characterised by white light interferometry. Two methods for calculating the stress concentration factor using the surface roughness data are proposed, and the results of each approach are presented and compared. Moreover, a finite element model was developed, in order to analyse the stress field when subsurface porosity is present. The fatigue lifetime estimates suggest that the lifetime of components may differ up to two orders of magnitude, depending on the build orientation.     

电化学表面处理对碳纤维结构及性能的影响

采用新型电化学表面处理设备,以10%（质量分数）NH4HCO3溶液为电解质,对12KPAN基碳纤维进行连续化的表面处理,探索了在提高碳纤维/树脂复合材料层间剪切强度的同时降低碳纤维本征拉伸强度损失的结构变化特征及规律。利用SEM、XRD、XPS、Raman等方法研究了改性前后碳纤维表面的物理和化学状态、晶体尺寸和表面有...