Vacuum brazing of Si/SiC ceramic composite and Invar alloy using TiSOCu-W filler metals

Si/SiC ceramic composite and lnvar alloy were successfidly joined by vacuum brazing using Ti5OCu-W filler metals into which W was added to release the thermal stress of the brazed joint. Microstructures of the brazed joints were irwestigated by scanning electron micrascope （SEM） and energy dispersive spectrometer （EDS）. The mechanical properties of the brazed joints were measured by shearing tests. The results showed that the brazed joints were composed of Ti-Cu phase, W phase and Ti-Si phase. W had no effect on the wettability and mobility of the .filler metals. The growth of Ti2 Cu phase was restrained, and the reaction between ceramic composite and filler metals was weakened. The specimen, brazed at 970°C for 5 rain, had the maximum shear strength of 108 MPa at room temperature.

Metal-ceramic Bond Mechanism of the Co-Cr Alloy Denture with Original Rough Surface Produced by Selective Laser Melting

The porcelain fracture caused by low metal-ceramic bond strength is a critical issue in porcelain fused to metal（PFM） restorations. Surface roughening methods, such as sand blasting, acid etching and alkaline degreasing for the metal matrix are used to increase bond strength. However, the metal matrix of PFM processed by selective laser melting（SLM） has natural rough surface. To explore the effect of the original roughness on metal-ceramic bond strength, two groups of specimen are fabricated by SLM. One group of specimen surface is polished smooth while another group remains the original rough surface. The dental porcelain is fused to the specimens＇ surfaces according to the ISO 9693：1999 standard. To gain the bond strength, a three-point bending test is carried out and X ray energy spectrum analysis（EDS）, scanning electron microscope（SEM） are used to show fracture mode. The results show that the mean bond strength is 116.5 16 MPa of the group with rough surface（Ra= 17.2）, and the fracture mode is cohesive. However, when the surface is smooth （Ra =3.8）, the mean bond strength is 74.5 MPa _＋ 5 MPa and the fracture mode is mixed. The original surface with prominent structures formed by the partly melted powder particles, not only increases surface roughness but also significantly improves the bond strength by forming strong mechanical lock effect. Statistical analysis （Student＇s t-test） demonstrates a significant difference （p〈0.05） of the mean value of bond strength between the two groups. The experiments indicate the natural rough surface can enhance the metal-ceramic bond strength to over four times the minimum value （25 MPa） of the ISO 9693：1999 standard. It is found that the natural rough surface of SLM-made PFM can eliminate the porcelain collapse defect produced by traditional casting method in PFM restorations.

Fabrication of ceramic layer on an Al-Si alloy by MAO process

The MAO (Micro-Arc Oxidation) process is applied to a eutectic Al-Si alloy(Al-12.0 percent Si-l.0 percent Cu-0.9 percent Mg (mass fraction)). The oxide ceramic layer wasfabricated with about 220 mum thickness and 3000 Hv micro-hardness. By XRD (X-ray diffractometry)and DSC (differential scanning calorimetry) analyses, the oxide layer consists of amorphous Al_2O_3,which is distinct from the results reported by the other researchers. The SEM photographs of suchlayer show that the layer is fixed tightly on the substrate alloy. So this alloy can he used in thehigh temperature and friction environment alter it is treated with such process.

Interaction between AE44 magnesium alloy and SiC-Al_2O_3-SiO_2 ceramic foam

The interaction between a molten magnesium alloy AE44 and a SiC?Al2O3?SiO2 ceramics and the resulting reaction products were studied. The samples were investigated using optical and electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction. SiO2was predominantly reduced by Mg during the contact of the magnesium-rich melt with the ceramics. The main reaction product was MgO, whilst Si dissolved in the melt. Two novel tetragonal phases formed at the interface: AlSiRE and AlMgSiRE, having a specific mutual crystallographic orientation relationship. The interactions resulted in strongly connected interfaces between the metal and ceramics after short interaction time; however, interactions lead to disintegration of the ceramics after longer contact time.

NOTCH WEAR OF MACHINING NICKEL BASED ALLOYS WITH CERAMIC TOOLS

The performances of mixed ceramic and sialon ceramic tools in machining nickel based alloy are tested.The negative cutting edge inclination and small tool lead angle are recommended for reducing ceramic tool failure. So called“notching at depth of cut”is not actually at the depth of cutting line, but out of cutting area。 The real reason of notching is caused by shocking of “sawtooth”on sawtooth- shaped burr and fin- shaped edges of chip

前牙In-Ceram全瓷冠与金属烤瓷冠修复临床疗效对比

目的:评价In-Ceram全瓷冠在前牙修复的临床效果。方法:对30例58颗前牙进行全瓷冠修复(全瓷冠组),以加利福尼亚牙科协会(CDA)评价标准对戴用0.5～2年后的冠边缘完整性、解剖外形、表面及颜色等进行临床观察评价,结合美观效果、牙龈刺激及失败率等指标,与同期制作的金属烤瓷修复体(金属烤瓷冠组)进行对比。结果:全瓷冠在颜色(满意率:全瓷冠91.4%,烤瓷冠75.8%)及解剖外形(满意率:全瓷冠91.4%,烤瓷冠77.3%)满意度方面优于烤瓷冠组(均P<0.05)。全瓷冠出现牙龈炎的概率小于烤瓷冠,2组在1.5年以后差别有统计学意义(P<0.05)。全瓷冠组不会出现龈缘灰线,金属烤瓷冠组在1年后就会有龈缘灰线出现,2组差别有统计学意义(P<0.05),在修复失败率及边缘完整性方面,2组差别无统计学意义(P>0.05)。结论:In-Ceram全瓷冠用于前牙修复可取得良好效果。

Microstructure and properties of an Al–Ti–Cu–Si brazing alloy for SiC–metal joining

An Al–Ti–Cu–Si solid–liquid dual-phase alloy that exhibits good wettability and appropriate interfacial reaction with SiC at 500–600°C was designed for SiC–metal joining. The microstructure, phases, differential thermal curves, and high-temperature wetting behavior of the alloy were analyzed using scanning electron microscopy, X-ray diffraction analysis, differential scanning calorimetry, and the sessile drop method. The experimental results show that the 76.5Al–8.5Ti–5Cu–10Si alloy is mainly composed of Al–Al2Cu and Al–Si hypoeutectic low-melting-point microstructures (493–586°C) and the high-melting-point intermetallic compound AlTiSi (840°C). The contact angle, determined by high-temperature wetting experiments, is approximately 54°. Furthermore, the wetting interface is smooth and contains no obvious defects. Metallurgical bonding at the interface is attributable to the reaction between Al and Si in the alloy and ceramic, respectively. The formation of the brittle Al4C3phase at the interface is suppressed by the addition of 10wt% Si to the alloy. © 2017, University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg.

Dual-function protective layer for highly reversible Zn anode

The thermodynamic instability of zinc anodes in aqueous electrolytes leads to issues such as corrosion,hydrogen evolution reactions(HER), and dendrite growth, severely hindering the practical application of zinc-based aqueous energy storage devices. To address these challenges, this work proposes a dualfunction zinc anode protective layer, composed of Zn-Al-In layered double oxides(ILDO) by rationally designing Zn-Al layered double hydroxides(Zn-Al LDHs) for the first time. Differing from previous works on the LDHs coatings, firstly, the ILDO layer accelerates zinc-ion desolvation and also captures and anchors SO_(4)^(2-). Secondly, the in-situ formation of the Zn-In alloy phase effectively lowers the nucleation energy barrier, thereby regulating zinc nucleation. Consequently, the zinc anode with the ILDO protective layer demonstrates long-term stability exceeding 1900 h and low voltage hysteresis of 7.5 m V at 0.5 m A cm^(-2) and 0.5 m A h cm^(-2). Additionally, it significantly enhances the rate capability and cycling performance of Zn@ILDO//MnO_(2) full batteries and Zn@ILDO//activated carbon zinc-ion hybrid capacitors.This simple and effective dual-function protective layer strategy offers a promising approach for achieving high-performance zinc-ion batteries.

Effect of Surface Layer Structural-Phase Modification on Tribological and Strength Properties of a TiC–(Ni–Cr) Metal Ceramic Alloy

This paper reports TiC–（Ni–Cr） metal ceramic alloy（ratio of components 50：50） with nanoscaled components formed in the surface layer and smoothly transformed into the initial inner structure throughout the material under pulsed electron irradiation of the alloy surface. Principal changes in the surface layer are ascribed to the formation of gradient structure leading to the increase in wear resistance of the surface layer, drop of friction coefficient and improvement of specimen bending resistance when stressing on the irradiated surface side. The above changes of tribological and strength properties in the surface layer under pulsed electron irradiation become more apparent with increasing atomic mass of a plasma-forming inert gas.

Pd-Y合金膜的MOCVD研制

采用金属有机化合物的化学气相淀积法 ,以 β-二酮螯合物为源物质 ,在多孔 Al2 O3 衬底上成功制备了超薄钯钇合金膜 .用 Pd( Ac Ac) 2 +Y( Ac Ac) 3 混合源制备的钯钇合金膜的晶粒尺寸 ( 2 1nm× 10 nm )比单独用 Pd( Ac Ac) 2 制备的钯膜的尺寸 ( 3 0 nm× 10 nm )小 . XPS研究发现 ,制备的 Pd-Y合金膜中 Y/Pd比小于源物质的 .氢的透气性实验表明 ,合金膜的氢渗透率高于 Pd膜 ,且在 2 0 0～ 3 5 0℃范围内渗透率稳定 .

钛合金表面激光熔覆NiCrBSi(Ti)-TiC涂层

在TC4合金表面进行了激光熔覆NiCrBSi TiC ,Ti TiC金属陶瓷复合涂层的试验 ,对涂层的组织和显微硬度进行了分析和测试。结果表明 ,NiCrBSi TiC涂层的组织是在初晶γ Ni和γ Ni,Ni3 B ,M2 3 (CB) 6 ,CrB多元共晶的基底上均匀地分布着TiC颗粒 ,在激光熔覆过程中TiC颗粒只是边缘发生了溶解或熔化 ;在Ti TiC涂层中 ,TiC颗粒全部溶解或熔化 ,冷却时以枝晶形式重新析出。NiCrBSi TiC涂层的显微硬度 (HV90 0～ 110 0 )明显高于Ti TiC的涂层的显微硬度 (HV5 0 0～ 70 0 )。

牙科Co-Cr烤瓷合金的金瓷结合性研究

通过对牙科Co-Cr烤瓷合金的XRD、SEM和EDS分析、热膨胀系数及金瓷结合强度的测定,研究了合金的成分、热膨胀系数及固态相变对其金瓷结合性的影响。试验测得Co-Cr合金的金瓷结合强度为40.9MPa,高于标准YY0621-2008中要求的25MPa。合金的显微组织由fcc钴的固溶体、hcp钴的固溶体、岛状的金属间化合物及σ相构成。合金与陶瓷的热膨胀系数差为(0.5～0.6)×10-6/℃。烤瓷过程中,合金中fcc相向hcp相的转变以及σ相的析出,降低金瓷匹配性,增大烤瓷修复体的崩瓷、裂瓷率。

铜镍合金/NiFe_2O_4-10NiO复合陶瓷惰性阳极的制备及其性能研究

以NiO、Fe2O3和铜、镍为主要原料,采用高能球磨—固相烧结法,制备出Cu-Ni-NiFe2O4-10NiO和(Cu-Ni合金)/NiFe2O4-10NiO金属陶瓷试样,研究了试样的物相组成、显微结构以及其体积密度、静态热腐蚀率、抗热震性和电导率。研究表明,合金粉的添加能够改善金属相的溢出现象并提高材料的物化性质。与Cu-Ni-NiFe2O4-10NiO金属陶瓷相比,合金粉均匀的弥散于陶瓷相中,减小了晶界间的势垒作用,使载流子更易通过晶界从而提高了试样的导电率,850℃时试样的电导率为60.7 S/cm;增大了材料的致密度;耐高温和抗冰晶石熔盐静态腐蚀率较低,平均腐蚀率降为12.62 mm/a;较大提高了试样的抗热震性。

金属烤瓷冠对龈沟液中IL-1β、AST及ALP水平的影响

目的:了解不同金属烤瓷冠对局部牙周组织造成的影响,以及龈沟液中白细胞介素(IL)-1β、天冬氨酸转氨酶(AST)和碱性磷酸酶(ALP)水平与牙周组织健康状况的关系。方法:选择28例接受金属烤瓷冠修复患者的上颌切牙(共34颗)为实验对象,其中镍铬合金烤瓷冠19颗,金铂合金烤瓷冠15颗。以患牙的对侧同名健康牙为对照组,在烤瓷冠戴入6～8个月后复诊,并对龈沟液中IL-1β、AST、ALP水平进行分析。结果:镍铬合金烤瓷组IL-1β及ALP水平均高于对照组,差异有统计学意义;金铂合金烤瓷组IL-1β、ALP与对照组差异无统计学意义;两种金属烤瓷冠AST水平均普遍高于对照组,差异有统计学意义。结论:镍铬合金烤瓷冠对牙周组织的不利影响较明显,而金铂合金烤瓷冠修复前后各项指标变化不明显。龈沟液中IL-1β、AST及ALP的浓度水平可以较敏感地反应金属烤瓷冠对牙周组织的影响。

SiO_2陶瓷-TC4接头陶瓷侧的界面行为

采用AgCu/Ni复合中间层钎焊SiO_2陶瓷与TC4合金,形成良好接头;采用组织均匀,熔点为909.1℃的自制AgCuTiNi活性钎料对SiO_2陶瓷进行钎焊,形成良好接头.通过扫描电镜(SEM)和X射线衍射分析(XRD)等手段对上述两种钎焊试件的界面组织进行分析,研究Ti元素的活度对SiO_2陶瓷-TC4接头陶瓷侧界面行为的影响.结果表明,TC4/Ag Cu/Ni/SiO_2陶瓷接头的典型界面结构为TC4合金/Ti(s,s)+Ti_2(Ni,Cu)+Ti_2(Cu,Ni)/Ti_4O_7+TiSi_2/SiO_2陶瓷;AgCuTiNi/SiO_2陶瓷试件的典型界面结构为Ti2(Cu,Ni)/Ti(s,s)+Ti_2(Ni,Cu)+Ti_2(Cu,Ni)/Ti_4O_7+TiSi2/SiO_2陶瓷.钎焊温度为970℃,保温时间相同时,随着Ti元素活度的增强SiO_2陶瓷侧反应层厚度明显增加.钎焊温度为970℃,Ti元素活度相同时,随着保温时间的延长,SiO_2陶瓷侧反应层厚度增加.

Ni-Cr合金烤瓷冠桥崩瓷后树脂修补的研究

目的：探讨崩瓷树脂修复中,ClearfilTMSE BOND和Lute粘结剂的剪切粘结强度的差异。方法：镍铬（Ni-Cr）合金试件、烤瓷试件、新鲜离体上中切牙、烤瓷熔附金属全冠共60例,分6组,每组10例。1组：Ni-Cr合金＋Clearfil SE BOND＋复合树脂;2组：烤瓷＋Clearfi SE BOND＋复合树脂;3组：Ni-Cr合金＋Lute＋复合树脂;4组：烤瓷＋Lute＋复合树脂;5组：牙釉质＋Durafill Bond＋复合树脂;6组：烤瓷熔附Ni-Cr合金。1~5组修复材料均为Durafill vs口腔光固化复合树脂。镍铬合金和烤瓷试件表面分别用ClearfilTMSE BOND、Lute粘结剂粘结复合树脂,离体牙牙釉质用常规粘结剂粘结复合树脂,粘结剂按产品说明书使用,复合树脂用Durafill vs。经37℃恒温水浴24h后做剪切实验,进行统计分析。结果：ClearfilTMSE BOND~对镍铬合金与树脂的剪切粘结强度明显高于Lute粘结剂（P〈0.05）,对烤瓷的剪切粘结强度两者差异无统计学意义（P〉0.05）,且这3组和离体牙釉质与树脂的剪切粘结强度差异无统计学意义（P〉0.05）。结论：无需酸蚀或喷砂,ClearfilTMSE BOND~粘结剂对镍铬合金与树脂的粘结牢固有效。

Ni-Si激光合金化层的模糊综合评价

针对拉丝模的工作表面进行激光合金化处理,研究其表面性能的改善情况。影响激光合金化层性能的评价因素很多,且这些因素之间相互联系、相互影响,并共同构成了一个庞大的模糊系统。运用模糊综合评价的数学模型对45钢表面的激光合金化层的性能,结合各种评价因素的性质、加权关联、重要程度进行排序,做出一种十分有效且全面评价的多因素决策。

镍基Al_2O_3-TiB_2金属陶瓷粉末机械合金化机制研究

本文研究了添加不同质量分数的Ni对机械合金化合成Al_2O_3-TiB_2金属陶瓷粉末的影响。应用X射线衍射仪、扫描电镜对球磨不同时间后的产物进行了物相和颗粒形貌的分析。结果表明:不含Ni粉的Al、TiO_2和B_2O_3的混合粉末,在机械合金化12 h后,按照化学方程式10Al+3TiO_2+3B_2O_3=5Al_2O_3+3TiB_2发生固相反应,获得Al_2O_3、TiB_2复相组织;当加入Ni粉后Al、TiO_2和B_2O_3的混合粉末,由于在机械球磨过程中,Ni优先与Al形成中间相NiAl,NiAl比Al更容易与TiO_2及B_2O_3发生反应,按照化学方程式10NiAl+3TiO_2+3B_2O_3=5Al_2O_3+3TiB_2+10Ni发生固相反应,获得Al_2O_3、TiB_2复相组织;使得机械合金化时间随着Ni粉加入量的增大而减小,当添加质量分数为5%、10%、15%、20%、25%和30%的Ni粉后,分别在机械合金化12 h、10 h、8 h、8 h、6 h和4 h后,得到Al_2O_3、TiB_2复相组织。

激光合金化SiC-Ni金属陶瓷XRD分析与讨论

本文针对拉丝模的工作表面进行激光合金化处理,研究其表面性能的改善情况。文中运用XRD评价45#钢表面的激光合金化层的性能,结合各种评价因素的性质,做出一种十分有效且全面评价的多因素决策。实验结果证明这种评价方法是一条科学、客观的可行途径。

用 Al-Sn 合金作插入金属进行扩散连接的研究进展

综述了用Ａｌ－Ｓｎ合金作插入金属进行扩散连接的研究进展。研究表明，用Ａｌ－Ｓｎ合金作插入金属可以将陶瓷与金属连接起来。