激光功率对不锈钢表面清洗效果影响的研究

利用激光清洗技术对不锈钢表面进行清洗试验,研究不同激光功率(300W、400W、500W)对清洗效果的影响。通过SEM和EDS分析不锈钢表面清洗前后的表面形貌及成分分布;利用白光干涉仪检测不锈钢表面粗糙度及清洗厚度。结果表明,随着激光功率的增加,不锈钢表面氧化物逐渐分解剥落,清洗厚度不断加深,在500W时达到50pm,并且造成基体部分损伤;粗糙度值先降低后增加,在400 W时达到最低值0.38 pm。激光清洗的清洗阈值近似为3.96×103 W/cm2,基体损伤阈值在5.52×103 W/cm2左右,不锈钢表面氧化层在400W时达到最佳激光清洗效果。     

C~+离子注入SiGe衬底提高NiSiGe表面和界面特性研究

本文主要研究了不同剂量C+离子预先注入Si0.8Ge0.2衬底后,对Ni和Si0.8Ge0.2反应的影响。研究结果充分表明:C+离子注入的Si0.8Ge0.2衬底,降低了Ni和Si0.8Ge0.2反应的速度,提高了NiSi0.8Ge0.2的热稳定性。此外,我们发现C原子分布在NiSi0.8Ge0.2/Si0.8Ge0.2的界面,大幅度降低了NiSi0.8Ge0.2表面和NiSi0.8Ge0.2/Si0.8Ge0.2界面的粗糙度,高剂量C+注入的样品效果更为明显。     

试验速度对冷轧带钢表面粗糙度测试结果的影响

GB/T 2523-2008要求接触式表面粗糙度仪的触针移动速度一般为0.5mm·s~(-1),为提高接触式表面粗糙度仪的触针移动速度从而缩短表面粗糙度的检测周期、提高检测效率,开展了专项对比试验,分析了试验速度对表面平均粗糙度Ra和峰值数PPI测试结果的影响。结果表明:Ra为0.6～1.6μm的试样,试验速度为1.0mm·s~(-1)和1.5mm·s~(-1)时测得的Ra和PPI与试验速度为0.5mm·s~(-1)时测得的没有显著性差异;当试验速度增大为2.0mm·s~(-1)时,测得的Ra和PPI与试验速度为0.5mm·s~(-1)时测得的存在显著性差异。     

铬及铍表面辉光放电清洗的研究

本文对He辉光放电清洗后的铬（Cr）表面杂质去除情况和铍（Be）样品真空出气量变化进行了实验研究。使用场发射扫描电镜和表面质量测量仪对比观察了不同放电参数处理后的Cr样品表面，结果显示在放电功率为200～300W、放电室压强为1～10Pa、清洗时间为10-20min时可较好地清除表面杂质和降低表面粗糙度；对辉光放电处理前后Be样品出气情况的实验对比结果显示，清洗后1h内总出气量约降为清洗前的1／6。     

基于散斑强度相关函数的表面粗糙度测量方法

激光经过被测表面反射和散射后,通过自由空间传播至观察面上形成散斑图像,其统计分布依赖于被测表面的微观形貌。分析此散斑图像的二阶统计特性,导出了强度变化的相关函数和表面粗糙度参数之间的关系。以表面粗糙平均值Ra分别为0.1靘, 0.2靘, 0.4靘和0.8靘的平磨标准金属样块形成的散斑图像为例,根据强度变化相关函数的离散化定义,计算得到该相关函数值。结果表明,表面越粗糙,散斑越分散,强度变化的相关函数波动越大。因此,该参数可以反映不同的粗糙面,用其作为表征表面粗糙度的特征参数,扩大了测量范围。该方法实验系统简单,对于实际测量环境要求不高,对震动不是非常敏感,适于在线测量。     

表面粗糙度对钛合金压力连接界面微观组织与性能的影响

目的研究表面粗糙度对钛合金压力连接界面微观组织与性能的影响。方法采用压力连接方法,对不同表面粗糙度的TC4合金进行连接试验,观察连接界面处的微观组织形貌,定量分析不同表面粗糙度下,连接界面空洞尺寸与界面结合率的变化规律,通过剪切试验,测定连接界面的剪切强度,并观察剪切断口形貌。结果在连接温度为850℃、连接压力为30 MPa、连接时间为10 min的条件下,连接表面粗糙度Ra由0.34μm减小至0.12μm时,连接界面处的空洞逐渐由尺寸较大的长条状转变为微小的圆形空洞,空洞完全消失的区域逐渐增多;平均空洞尺寸由2.7μm减小至1.4μm,连接界面结合率由88.2%提高至94.6%;连接界面剪切强度由682 MPa增大至762 MPa,剪切断口呈现韧性断裂特征的区域显著增大。结论表面粗糙度对钛合金压力连接界面微观组织和剪切强度影响显著,降低表面粗糙度有利于提高钛合金压力连接质量。     

对DIN 10049更改ISO 4288取样长度选用规则的检验试验

针对各汽车企业标准都要求汽车用薄钢板表面粗糙度Ra<2μm的客观条件,对多种不同类型表面形貌特征的样板采用不同的取样长度(以0.8mm和2.5mm为主)和取样区间数进行了表面粗糙度测量对比试验,以检验欧洲标准DIN EN 10049-2006将汽车用薄钢板表面粗糙度测量的取样长度由ISO 4288:1996中的0.8mm更改为2.5mm是否科学合理。结果表明:采用0.8mm和2.5mm取样长度测得不同薄板的表面粗糙度变化情况不同,两者各有大小,因样板的表面结构特征而异,与"取样长度增大,测量的Ra值也应相应增大"这一传统观点并不相符;从促进世界贸易角度出发,在汽车用薄钢板Ra测量中坚持遵循ISO 4288:1996选用0.8mm的取样长度有利于数据溯源。     

纵-弯复合振动超声挤压加工试验研究

为研究挤压加工时静压力、进给量和挤压速度等工艺参数对试件表面质量的影响,在挤压加工中引入纵-弯复合振动后对Q235钢轴件端面进行处理,并与普通挤压加工进行对比,基于正交试验结果构建了挤压加工后表面粗糙度和表面里氏硬度二次回归预测模型.试验发现:在相同加工工艺参数下,在普通挤压加工中引入纵-弯复合超声振动后获得的表面粗糙度Ra值更小,而表面里氏硬度值显著提高;采用两种挤压加工方法后工件表面粗糙度Ra值均随着静压力和进给量的增加而增大,而挤压速度的影响很小,进给量对表面粗糙度的影响最为显著;工件经超声挤压加工时静压力越大,则获得的表面硬度越大,且表面硬度随进给量的增大先增大后减小,而普通挤压加工后表面硬度随静压力和进给量的增大先增后减,且在两种加工方式下工件表面硬度基本不受挤压速度的影响.纵-弯复合振动超声挤压加工工艺适合Q235钢表面强化处理,构建的表面粗糙度和硬度的预测模型可用于指导Q235钢表面强化处理工艺生产.     

TC4钛合金超声深滚表面强化技术的研究

采用一种新型表面机械强化技术-超声深滚技术(UDR)对钛合金试样进行了表面强化处理。研究了超声深滚处理对试件的残余应力、加工硬化和表面形貌及表面粗糙度的影响。结果表明:超声深滚处理引入了高幅值、大深度的残余压应力、加工硬化量适度并且显著降低了表面粗糙度。根据以上结果分析了该技术的优势和应用前景。     

表面粗糙度对热轧不锈钢复合板界面质量的影响

为了研究板坯表面粗糙度对不锈钢复合板界面特性的影响,基于MSC.Marc软件建立了复合板界面非共节点热轧三维热力耦合模型,分析了双金属间摩擦因数对轧制变形区界面黏接特点的影响规律,同时进行了不同表面粗糙度板坯的热轧试验及性能评估试验.研究结果表明,随着双金属间摩擦因数的增大,轧制变形区内的黏接现象越早发生;较大的板坯表面粗糙度抑制了界面碳元素的扩散,同时也容易导致界面产生夹杂物和孔洞等缺陷.拉剪试验表明,粗糙度Ra=7.6μm的复合板的剪切强度最高,达到384.81 MPa,Ra=1.6μm的复合板的剪切强度为365.85 MPa,两种拉剪试样均为韧性断口.Ra=15.6μm的复合板由于界面存在孔洞缺陷,发生了脆性断裂,拉剪强度最低,为321.74 MPa.     

钛合金表面微粗糙化对成骨细胞黏附及增殖行为的影响

采用表面机械研磨(SMAT)法对Ti-25Nb-3Mo-3Zr-2Sn(TLM)钛合金处理15min,而后将处理前后的钛合金样品与成骨细胞共培养1h、24h。采用X射线衍射(XRD)、光学显微镜(OM)、透射电镜(TEM)、扫描电镜(SEM)、电子能谱(EDX)及激光共聚焦显微镜(CLSM)对处理前后样品表面的结构进行了分析,结果显示SMAT处理不会改变TLM钛合金的物相、晶粒尺度及化学组成,处理前后物相均由单一的β相组成,晶粒尺寸均在10~20μm且没有引入新的杂质元素,但SMAT处理会改变TLM钛合金的表面粗糙度,处理前的样品表面平整,平均粗糙度Ra为(0.2±0.03)μm,而处理后的样品表面坑洼不平,平均粗糙度Ra增至(2.6±0.4)μm。随后的细胞实验结果显示,对比SMAT处理前,成骨细胞在处理后的微粗糙表面铺展得更为充分,增殖得更加迅速。研究表明,SMAT处理可以改善TLM钛合金表面的成骨细胞生长环境,从而为开发出更符合临床应用的钛金属种植体提供新的思路。     

Computer Vision Based Non-contact Surface Roughness Assessment Using Wavelet Transform and Response Surface Methodology

This paper describes a new non-contact measurement approach in characterizing manufactured surfaces. Computer vision is applied to capture digital images of three types of anisotropic steel specimen surfaces from shaping, grinding, and polishing processes. Multiresolution wavelet decomposition is used to obtain signatures of surface profiles from the digital images. Relationships between these signatures and surface roughness parameters (Ra and Rq) are built by response surface methodology (RSM). The proposed models thus developed are suitable for predicting roughness in terms of the roughness parameters. Experimental results show that the proposed approach successfully correlates wavelet signals to Ra and Rq values. In addition, they also show repeatable gage capabilities. The proposed method is a good candidate for on-line, real-time surface roughness inspection when specimens of known surface roughness are available.     

激光选区熔化TC4钛合金高氯酸电解抛光工艺研究

以高氯酸溶液为电解液,对激光选区熔化TC4钛合金试样进行电解抛光工艺试验,研究了电流密度、时间、温度、阴极材料等相关参数对试样的粗糙度、失重率、减薄率的影响,同时,对抛光处理后试样的表面形貌进行了分析。研究结果表明,按高氯酸10m L、冰乙酸100m L、水12m L配比的混合电解液,在电流密度为(0.27~0.37)A·cm^-2,温度(30~35)℃,时间(15~20)min的条件下进行电解抛光所得的效果较好。试样表面粗糙度Ra由13.66μm降至1.52μm,厚度减薄率在(6~7)%左右,试样表面平整光亮,均一性较好。     

Wettability of AlN with different roughness, porosity and oxidation state by commercial Ag-Cu-Ti brazes

The effects of porosity (about 27%), of roughness (Ra = 0.17–0.20 μ m versus Ra = 0.02–0.03 μm) and of pre-oxidation (air, 1250^°C, 30 min) on wettability and contact interaction of AlN with commercial brazing alloys of Ag-Cu-Ti composition were studied. Wettability was determined by the sessile drop method. The interface interaction was identified by SEM and microprobe analysis. Experimental data for porous, pre-oxidized and rough samples are compared with data for dense samples polished to Ra = 0.02–0.03 μ m not subjected to pre-oxidation. The results show that for these systems surface roughness does not influence the contact angle value significantly. Pre-oxidation of the AlN, however, tends to reduce wettability as a result of the replacement of braze/AlN interaction by braze/surface aluminium oxide interaction. Contact angles for porous samples are higher by about 20–30° than for dense samples.     

Fracture surface roughness and toughness of Al2O3-platelet reinforced glass matrix composites

The correlation between fracture surface roughness and fracture toughness of alumina platelet reinforced borosilicate glass matrix composites was investigated. With increasing volume fraction of platelets both fracture toughness and fracture surface roughness increase. The fracture roughness parameter Ra was determined by the profilometric technique. A linear correlation was found between the fracture toughness and the Ra values of the composites. Scanning electron microscopy observation of fracture surfaces confirmed that surface roughness is related to a crack deflection process. Crack deflection is thus one of the toughening mechanisms acting in these composites.     

Evaluation of surface characteristics of dental composites using profilometry,scanning electron,atomic force microscopy and gloss-meter

The aim of this in vitro investigation was to compare various roughness and topography measurement methods to characterize the surface quality in several types of resin composites. The initial surface quality of several resin composites was compared. The materials evaluated were of three categories: i) hybrid: TPH Spectrum; ii) reinforced microfill: Micronew and iii) microhybrid: Synergy Duo, Esthet-X, Point.4 and Palfique Estelite. Three Groups of identical disk-shaped specimens (10 × 1.5 mm) were prepared from each material (n = 6) and polished with Soflex discs. Macro-roughness (Ra) was measured with Group 1 by 2-D profilometry. Atomic Force Microscopy (AFM) gave 3-D images and micro-roughness (Ra) of Group 2. Surface optical gloss at 60^∘ was determined for Group 3. Specimens of each material were also studied by scanning electron microscopy. Macro-Ra values (μm) ranged from 0.30 to 0.56. Micro-Ra values ranged from 0.03 to 0.14 and they differed from macro-Ra values in ranking order. Percentage Gloss values ranged from 30.6 to 70.1%. The results revealed that micro-roughness showed a high correlation with gloss values (r = 0.93), whilst macro-roughness did not (r = 0.62). Moreover, the AFM method showed higher capability to distinguish surface roughness compared with the 2-D profilometry and to reveal more detailed definition of surface texture than the examination under SEM.     

Mechanical properties of Pt-Ir and Ni-Ir binary alloys for glass-molding dies coating

In this study, the different compositions of Pt-Ir and Ni-Ir alloys were deposited by utilizing ion source assisted magnetron sputtering system (ISAMSS). The surface roughness and crystallite size of the Pt-Ir and Ni-Ir coatings were analyzed by atomic force microscopy (AFM) and X-ray diffraction (XRD), respectively. In addition, coatings were soaked at 700 degrees and maintained 10 min under N2 atmosphere using a glass-molding machine. The annealed coatings for oxidation test were examined by energy dispersive X-ray spectrometry (EDS) and for microhardness and reduced modulus test were evaluated by nanoindentation instrucment. The cross-sectional structures between the Pt-Ir and Ni-Ir coating layer and substrates were also examined by field emission scanning electron microscope (FESEM). The results show that surface roughness Ra from 1.25 nm to 3.426 nm was observed with increasing the Ni elements. However, the Ra is less than 2 nm measured in Ir-based coatings doped with Pt concentrations under this study. With increasing Pt and Ni doping, the microhardness of both coatings decreased significantly and the values of reduced modulus of Pt-Ir alloys are larger than that of Ni-Ir alloys. After oxidation process, the oxygen concentration of Pt-Ir coatings is less than that of Ni-Ir coatings and the Pt-Ir coatings exhibit superior properties including oxidation resistance, low surface roughness and high reduced modulus over Ni-Ir coatings, especially for the high Pt concentration coatings such as Pt-Ir 2 (55.25 at.% Pt) and Pt-Ir 3 (79.42 at.% Pt) coatings. The surface roughnesses of all specimens annealed at 700 degrees C were slightly larger than as-deposited coatings. Moreover, due to the serious oxidation occurred in Ni-Ir 3 (73.45 at.% Ni) coatings, the value of reduced modulus of this specimen coating is the lowest and the corrsponding Ra value is the largest compared with the rest of Ir-based coatings in the oxidation testing.     

The influence of substratum topography on bacterial adhesion to polymethyl methacrylate

The effect of substratum roughness on the adhesion of Pseudomonas aeruginosa and Staphylococcus epidermidis was investigated using PMMA. A small increase in Ra values (0.04–1.24 m) resulted in a significant increase (P<0.05) in bacterial attachment. Subsequent increases in surface roughness (Ra=1.86–7.89 m) resulted in a decrease in adhesion, although adhesion was still higher than to the smooth surface. When the PMMA surfaces were coated with protein (bovine serum albumin), no difference (P<0.05) could be determined in the amount of protein adsorbed, irrespective of surface topography. However, the influence of the underlying topography on adhesion was still evident. Substratum topography is an important parameter affecting bacterial adhesion to surfaces.     

热镀锌基板粗糙度对钝化膜耐蚀性的影响

为了研究热镀锌基板粗糙度对其表面环保钝化膜耐蚀性的影响,在不同表面粗糙度的基板上制备相同膜厚的钝化膜,采用中性盐雾试验方法,分析了不同粗糙度热镀锌基板的耐蚀性;采用扫描电镜观察了钝化膜表面的成分分布.结果显示:在试验条件下,随着粗糙度的增加,表面钝化膜的厚度均匀性逐渐降低,耐蚀性逐渐变差;对于家电用热镀锌板,建议基板粗糙度Ra控制在1.0μm以下.     

Direct determination of oxygen by HPLC. 1. Basic principles of a sensitive and selective oxygen sensor

The basic principles of a novel, versatile, sensitive, and selective oxygen-sensing assay are presented in this paper. For the first time, liquid chromatography with electrochemical detection (at the hmde) has been used for the determination of oxygen. All factors concerning optimization of the chromatographic separation conditions and electrochemical detection with respect to direct determination of oxygen even in complex biological samples are discussed. Due to the combination of a chromatographic technique with amperometric detection, a high selectivity can be achieved. A direct and linear relationship between the oxygen concentration in the sample and the reduction current was verified in a large concentration range from saturation down to trace level oxygen concentrations. The novel oxygen-sensing assay provides a much higher sensitivity compared to conventional oxygen sensors. In principle, O(2) concentrations down to 4.5 × 10(-)(9) mol L(-)(1) O(2) (corresponding to a signal-to-noise ratio of 3) can be detected. Precision was determined by repeated measurements (n = 6) of air-saturated solutions (2.5 × 10(-)(4) mol L(-)(1) O(2), 20 °C, 920 mbar) which yielded relative standard deviations of lower than 0.2%.