化学微蚀刻法和微细电镀法制备微流控芯片金属模具工艺对比研究

针对化学微蚀刻法和微细电镀法制备微流控芯片金属模具进行了工艺对比研究。采用激光共聚焦显微镜分别检测表征由这两种加工工艺制备所得的模具微结构特征,对其侧壁陡度、尺寸均匀性、粗糙度进行对比分析。结果表明,化学微蚀刻法制备的模具微结构的侧壁呈不规则弧形、尺寸均匀性差,表面粗糙度较大 (R_a=3.58 μm)。而微细电镀法制备的模具微结构的侧壁则呈规则的梯形、尺寸均匀性好,表面粗糙度较小(R_a=0.65 μm)。微细电镀法制备的微流控芯片金属模具综合效果比化学微蚀刻好。     

加热温度对Al-Si涂层热成形钢组织及性能的影响

利用粗糙度仪、扫描电镜、硬度计、辉光放电原子发射光谱仪等检测方法,研究分析了热冲压成形工艺过程中的加热温度对Al-Si涂层22MnB5热成形钢组织及性能的影响。结果表明,随着加热温度的升高,Fe沿垂直于表面方向由热成形钢基体向Al-Si涂层表面的迁移量逐渐增大,O沿垂直于表面方向由Al-Si涂层表面向热成形钢基体的迁移量逐渐增大,且迁移的最大深度约为2.80 μm。Fe沿垂直于表面方向由热成形钢基体向Al-Si涂层表面的迁移量直接决定了Fe-Al-Si相的形态、生成位置及界面结合层厚度。随着加热温度的升高,Al-Si涂层表面粗糙度R_a、峰值计数R_pc值先增大后减小;当加热温度为930 ℃时,涂层表面粗糙度R_a达到最大值1.89 μm,峰值计数R_pc值达到最大值218。随着加热温度的升高,Al-Si涂层总厚度从27.78 μm增加至40.46 μm,界面结合层厚度从1.08 μm增加至15.11 μm。当加热温度为930 ℃时,热成形钢基体的硬度达到最大值505 HV0.2。     

不同表面粗糙度镍铬铝合金的高温氧化行为

采用热重法并结合X射线衍射、扫描电子显微镜、能谱仪等分析手段,研究在1000 ℃条件下Ni-10Cr-5Al (质量分数,%) 合金样品表面粗糙度对其氧化行为的影响。结果表明：经1000 ℃氧化215 h后,不同表面粗糙度的合金其氧化动力学均服从抛物线规律,并存在两个抛物线常数,氧化膜主要由Al₂O₃,NiCr₂O₄和NiAl₂O₄组成。随着表面粗糙度的增加,氧化增重越明显,同时氧化膜脱落越严重、氧化膜金属界面越起伏。其中,表面粗糙度对合金氧化的影响主要是在氧化前期阶段促进生成了尖晶石NiCr₂O₄和NiAl₂O₄氧化物。     

柠檬酸钝化9Cr1Mo钢在海洋大气环境中的耐蚀性

为了提高9Cr1Mo钢在海洋大气环境中的耐蚀性,采用柠檬酸和柠檬酸-氢氧化物复合钝化工艺对9Cr1Mo钢进行表面钝化处理,研究了两种钝化处理对其耐蚀性的影响,分析了柠檬酸钝化处理提升9Cr1Mo钢耐海洋大气腐蚀性能的原因。结果表明：未钝化处理的9Cr1Mo钢在模拟和实际海洋大气环境中均发生严重腐蚀;两种钝化处理后9Cr1Mo钢表面均形成了保护性钝化膜,确保9Cr1Mo钢在海洋大气环境中腐蚀78 d内不发生明显腐蚀,显著提高了9Cr1Mo钢耐海洋大气腐蚀性能;采用柠檬酸和柠檬酸-氢氧化物复合钝化工艺可以提高钝化膜中Cr₂O₃、Cr(OH)₃含量,且氧化物含量显著高于氢氧化物,钝化膜的稳定性和耐蚀性增强。     

热处理对铝合金2A12硬质阳极氧化膜粗糙度的影响

利用电炉、自制的硬质阳极氧化装置、扫描电镜、能谱分析、原子力显微镜和TR200粗糙度仪研究了热处理对硬质阳极氧化膜粗糙度的影响.结果表明:经固溶处理后,人工时效(T6)比自然时效(T4)后的基体表面粗糙;经化学抛光,基体表面粗糙度都降低;硬质阳极氧化后表面粗糙度都增加,且经T6处理后的表面粗糙度更大、增长更快;氧化时间约100 min时,粗糙度增长缓慢.     

Mar-M247高温合金900℃下的氧化行为研究

为探究燃气轮机用高温合金在服役环境中组织结构变化及其对合金氧化性能的影响,利用扫描电镜和能谱表征了MarM247镍基高温合金在900℃长时效后的显微组织,研究其在1000、3000、5000、8000h时效后的氧化性能。结果表明,时效1000h的氧化初期合金表面氧化物相变化较快,Al₂O₃氧化膜不完整,氧化膜增厚较快;随着氧化时间增加,富W氧化膜内生成大量孔洞和岛状不连续WO2,导致内层Al₂O₃膜界面发生剥落,外层氧化膜结构得到简化,内层Al₂O₃膜增厚且变得均匀;时效8000h后氧化层总厚度和内层Al₂O₃膜变化幅度明显减小,整个氧化膜结构趋于稳定。由于内层保护性Al₂O₃膜的增厚和结构均匀连续,使得合金的氧化性能提高。     

深冷处理对K6509钴基合金表面性能的影响

研究了K6509钴基合金样品在-196 ℃液氮中分别深冷24 h和48 h后的表面性能变化,并与未深冷样品进行对比。通过显微组织分析、XRD成分分析、硬度分析等技术手段研究了深冷处理对钴基合金表面性能的影响,并分析了深冷处理和滚磨光整加工后表面粗糙度和形貌的变化。结果表明:钴基合金在深冷处理24 h时,有部分碳化物发生粗化,同时伴随着细小碳化物析出,深冷48 h时细小碳化物减少,碳化物粗化现象消失,显微组织变得均匀;通过XRD图谱发现,深冷过程中相组成没有发生变化,但含M₂₇C₆碳化物的共晶相和含M₇C₃碳化物的共晶相出现峰移现象,M₂₇C₆碳化物相衍射峰强度发生明显变化;延长深冷时间能够显著提高硬度,深冷48 h硬度提高了17.6%;选择合理的深冷时间与滚磨光整加工相结合能显著提高表面质量,经深冷48 h+滚磨光整处理后,表面粗糙度下降最多,R_a由1.215 μm降到0.662 μm,其表面缺陷明显减少,表面一致性好。     

纯Sn焊料表面高温氧化膜的腐蚀演化行为（英文）

对150℃高温时效条件下纯锡焊料表面氧化膜形貌、组成、厚度及耐蚀性的演化行为进行研究。结果表明,高温时效加速焊料表面原有自然氧化膜层中的Sn(OH)₄向SnO₂转变,同时加速新鲜Sn基体的氧化,从而使纯Sn焊料表面氧化膜厚度和粗糙度随时效时间的延长逐渐增加。然而,表面氧化膜层的耐蚀性随时效时间的延长呈先增强而后减弱的趋势。此外,还对纯Sn焊料表面氧化膜层的成膜机制及膜层演化机制进行讨论。     

用球差校正扫描透射电镜研究人工时效7075铝合金的耐蚀性（英文）

使用先进的球差校正扫描透射电子显微镜研究人工时效7075铝合金耐腐蚀性增强机制。通过阻抗谱、等效电路分析、极化测量和浸泡试验,研究人工时效7075铝合金在3.5%(质量分数) NaCl溶液中的腐蚀行为。结果表明,人工时效时间越长,7075铝合金的耐腐蚀性越好。这可能归因于扫描透射电镜技术揭示的以下显微组织特征：在过时效条件下,晶界处的铜偏析有助于延缓晶间腐蚀,在Al₁₈Mg₃(Cr,Mn)₂分散体表面形成的Mg(Zn,Cu)₂沉淀有效地将作为腐蚀阴极的分散体与铝基体隔离。这项研究证明,可以通过适当的合金化和人工时效来设计耐腐蚀合金的可能性。     

40Cr零件预应力淬硬磨削表面粗糙度值分析

表面粗糙度值是重要的表面完整性指标之一,其数值及分布特征对机械零件使用性能影响显著。为研究预应力淬硬磨削复合加工零件表面粗糙度值特征及影响机理,以40Cr材料为载体,开展预应力淬硬磨削复合加工试验,分别测量加工后试件表面切入段、中间段、切出段的表面粗糙度值,分析表面粗糙度值及分布特征与机理。结果表明:试件表面粗糙度值沿表面分布不均匀,从切入段到切出段表面粗糙度值呈逐渐增大的趋势。预应力一定时,随着磨削深度的增加,试件表面粗糙度值逐渐增加;磨削深度不变,预应力增大时试件表面粗糙度值降低,表面完整性有所提高。      

冷轧带钢表面形貌测试及其粗糙度均匀性控制研究

为了改善带钢表面粗糙度不均匀所引起的表面性能不良,采用双机架平整机进行了湿平整工艺试验,研究了平整毛化辊表面形貌及其遗传规律对带钢表面形貌的影响;改变了对毛化辊及平整后带钢表面形貌的测试方法,以R_sk及不同C值的R_pc为测试指标来评价平整毛化辊及平整后带钢表面形貌。结果表明：通过调整平整毛化辊的表面形貌,可以改变带钢对平整辊形貌的复制遗传规律,从而改善平整后带钢的表面形貌,其效果较调整其他平整工艺参数更为直接有效。通过减少平整毛化辊表面3×R_a的R_pc,平整后带钢的R_sk趋近于0,提高了R_pc(C=0.25μm)个数,平整后带钢表面的粗糙度更加均匀。因此,采用R_sk和不同C值的R_pc来评价平整毛化辊及平整后带钢的表面形貌,较采用粗糙度R_a值的评价方式,可以较好地评价粗糙度的均匀性。     

Surface characterization and immersion tests of TiNi alloy coated with Ta

The surface chemical composition and chemical state of Ti–50.6 at.% Ni alloy samples coated with tantalum by an arc ion plating method were investigated by X-ray photoelectron spectroscopy (XPS). The results of XPS survey and high resolution spectra show that a thin oxide film with Ta₂O₅ in the outmost layer and tantalum suboxides in the inner layer are formed on the tantalum coating as a result of natural passivation of Ta in the atmosphere. The Ni ion release with time from uncoated and coated samples immersed in 0.9%NaCl solution was also investigated by atomic absorption spectrometry (AAS). Compared to the coated samples, the uncoated samples show a higher release rate that decreases slightly with time. The degree of dissolution for the coated sample is reduced from 0.28 to 0.74 μg/cm² after 49 days, implying the coating has a beneficial effect on the inhabitation of Ni ion release from the TiNi substrate. The atomic force microscope (AFM) images and section analysis show that the root mean square (RMS) roughness increases from 10.349 to 65.587 nm, and the maximum roughness (R_max) increases from 36.027 to 278.22 nm, confirming that immersion in the NaCl solution results in roughening of the coating surface.     

Freeform surface finish of plastic injection mold by using ball-burnishing process

The objective of this study is to introduce the possible ball-burnishing surface finish process of a freeform surface plastic injection mold on a machining center. The design and manufacture of a burnishing tool was first accomplished in this study. The optimal plane ball-burnishing parameters were determined by utilizing the Taguchi’s orthogonal array method for plastic injection molding steel PDS5 on a machining center. Four burnishing parameters, namely the ball material, burnishing speed, burnishing force, and feed, were selected as the experimental factors of Taguchi’s design of experiment to determine the optimal burnishing parameters, which have the dominant influence on surface roughness. The optimal burnishing parameters were found out after conducting the experiments of the Taguchi’s L18 orthogonal table, analysis of variation (ANOVA), and the full factorial experiment. The optimal plane burnishing parameters for the plastic injection mold steel PDS5 were the combination of the tungsten carbide ball, the burnishing speed of 200 mm/min, the burnishing force of 300 N, and the feed of 40 μm. The surface roughness R_a of the specimen could be improved from about 1 to 0.07 μm by using the optimal burnishing parameters for plane burnishing. Applying the optimal burnishing parameters for plane burnishing to freeform surface plastic injection mold, the surface roughness R_a of freeform surface region on the tested plastic injection part could be improved from about 0.842 to 0.187 μm, through a comparison between using the fine milled and using the ball-burnished mold cavity.     

Performance of Chemical Vapor Deposited Boron-Doped AlN Thin Film as Thermal Interface Materials for 3-W LED: Thermal and Optical Analysis

Boron-doped aluminum nitride(B-Al N)thin films were synthesized on Al substrates by using chemical vapor deposition method by changing the synthesis parameters and were used as thermal interface material for high power light emitting diode(LED).The B-Al N thin film-coated Al substrate was used as heat sink and studied the performance of high power LED at various driving currents.The recorded transient cooling curve was evaluated to study the rise in junction temperature(T_j),total thermal resistance(R_(th-tot))and the substrate thermal resistance(R_(th-sub))of the given LED.From the results,the B-Al N thin film(prepared at process 4)interfaced LED showed low R_(th-tot)and T_jvalue for all driving currents and observed high difference in R_(th-tot)(DR_(th-tot)=2.2 K/W)at 700 m A when compared with the R_(th-tot)of LED attached on bare Al substrates(LED/Al).The T_jof LED was reduced considerably and observed 4.7°C as DT_jfor the film prepared using process 4 condition when compared with LED/Al boundary condition at 700 m A.The optical performance of LED was also tested for all boundary conditions and showed improved lux values for the given LED at 700 m A where B-Al N thin film was synthesized using optimized flow of Al,B and N sources with minimized B and N content.The other optical parameters such as color correlated temperature and color rendering index were also measured and observed low difference for all boundary conditions.The observed results are suggested to use B-Al N thin film as efficient solid thin film thermal interface materials in high power LED.     

Adaption of graded Cr/CrN-interlayer thickness to cemented carbide substrates' roughness for improving the adhesion of HPPMS PVD films and the cutting performance

High Power Pulsed Magnetron Sputtering (HPPMS) techniques jointly with the deposition of a graded Cr/CrN-nanointerlayer on cutting inserts can increase the film adhesion and consequently the tool life. These improvements depend on the roughness of the employed cemented carbide substrates. The investigations described in the present paper intend to explain the effect of Cr/CrN-interlayer thickness and substrate roughness on the coating adhesion and cutting performance. To attain various roughnesses, the applied cemented carbide inserts were superficially treated. These treatments were grinding at a medium roughness level, or grinding with subsequent polishing for enhancing the surface integrity and finally, in all cases, micro-blasting by fine Al₂O₃ grains. After Ar-ion etching, graded Cr/CrN adhesive layers with different thicknesses were deposited by HPPMS technology on the variously pretreated substrates. Subsequently, an approximately 3 μm thick (Ti,Al)N film was deposited by HPPMS PVD on all used inserts. Rockwell C indentations and inclined impact tests were performed to assess qualitatively and quantitatively the films' adhesion. The cutting performance of the coated tools was investigated in milling of 42CrMo4 QT. FEM supported calculations of the developed stresses during the material removal process contributed in explaining the obtained tool wear results. In these calculations, the adhesion, dependent on the substrate roughness characteristics and on the adhesive interlayer thickness, was taken into account. The results revealed that the effectiveness of HPPMS adhesive graded Cr/CrN-nanointerlayer strongly depends on the substrate surface integrity and on the interlayer thickness. Thus, the film adhesion and consequently the cutting performance can be significantly improved if the interlayer thickness is adapted to the substrate roughness.     

纳米金刚石涂层刀具高速铣削7075铝合金的工艺参数优化

采用热丝CVD法制备纳米金刚石薄膜涂层刀具,利用场发射扫描电子显微镜表征薄膜的表面形貌,并用已制备的CVD金刚石涂层刀具,在无润滑干切条件下高速铣削7075铝合金工件,对其精铣工艺参数进行单因素及正交试验,探索精铣后工件的表面粗糙度变化规律并进行工艺参数优化。结果表明:随着主轴转速n从5000 r/min提高到8000 r/min, 工件平均表面粗糙度在逐级缓慢降低;当进给速度v_f在1000～7000 mm/min范围内,随着v_f提高工件平均表面粗糙度快速增大,在v_f为7000 mm/min时,其值达1.790 μm;当轴向切削深度a_p在0.1～0.4 mm范围内,随着a_p提高,工件平均表面粗糙度逐步增大,但a_p在0.2 mm之后其增大趋势变缓。对7075铝合金工件精铣表面粗糙度影响最大的是v_f,其次为n,a_p的影响最弱;其精铣的最优参数组合是a_p=0.2 mm、v_f=1 000 mm/min、n=8 000 r/min,精铣后的表面粗糙度平均值为0.516 μm。选用纳米金刚石薄膜涂层刀具精铣7075铝合金时,为得到较低的表面粗糙度,应选择高主轴转速、低进给速度、合适的轴向切削深度。      

无铬复合钝化膜的微观组织结构及耐腐蚀性能

目的解决热镀锌钢板表面六价铬钝化工艺所产生的环境污染问题。方法以钼酸铵、纳米硅溶胶、单宁酸、硅烷偶联剂KH151和KH792为主要原料配制新型环保的无铬复合钝化液,在镀锌板表面制备钝化膜。采用扫描电子显微镜(SEM)、能谱仪(EDS)和X射线光电子能谱仪(XPS)分析无铬复合钝化膜表面的微观形貌、元素组成和化学成分,用电化学工作站测试Mo元素对镀锌板耐蚀性的影响,使用中性盐雾实验研究不同皮模量时膜层的耐蚀性。结果无铬复合钝化膜中的Mo元素可以抑制微裂纹的产生和发展,阻挡腐蚀性介质向金属基体扩散,提高复合硅烷膜的电阻。复合钝化膜的电化学交流阻抗比硅烷钝化膜提高了1.6倍,与六价铬钝化膜接近,可以有效抑制腐蚀电化学反应的发生,降低反应速度,提高膜层的耐蚀性。皮膜量为892 mg/m2时,膜层的腐蚀面积为0,耐蚀性达到六价铬钝化膜水平;皮膜量为1252 mg/m2时,耐蚀性能优异。结论制备的无铬复合钝化膜结合了硅烷钝化膜和钼酸盐钝化膜两方面的优点,提高了膜层的致密性和结合性,膜层耐腐蚀性接近/达到了六价铬钝化的效果。