Solid–liquid Interdiffusion Bonding of Cu/Sn/Ni Micro-joints with the Assistance of Temperature Gradient

A novel solid-liquid interdiffusion(SLID) bonding method with the assistance of temperature gradient(TG) was carried out to bonding Cu and Ni substrates with Sn as interlayer.The element distribution and grain morphology of interfacial intermetallic compound(IMC) in Cu/Sn/Ni micro-joints during both SLID and TG-SLID bonding and in the final Cu/(Cu,Ni)₆ Sn₅/Ni full IMC micro-joints were analyzed.Under the effect of Cu-Ni cross-interaction,interfacial(Cu,Ni)₆ Sn     

Bonding performance of diamond grit to a Co-Si alloy

The bonding performance between synthetic diamond grit and adhesive (Co-Si alloy ) in polycrystalline dianond conpact (PDC) has been investigated.The results indicate that the carbide-forming element Si diffuses towards the diamond grit and the quantity of Si elenent in the inter layer of diamond grit-adhesives is about two timeshigher than that in the other area .New compound SiC exists in the inter layer of diamond-adhesives.The formation of SiC enhances the strength and prolongs the service life of PDC .The sintering time is important to the formation of SiC.     

Effect of Bonding Temperature on the Microstructures and Strengths of C/C Composite/GH3044 Alloy Joints by Partial Transient Liquid-Phase（PTLP） Bonding with Multiple Interlayers

With the use of Ti/Ni/Cu/Ni multiple foils as interlayer,carbon/carbon(C/C) composite was bonded to Nibased superalloy GH3044 by partial transient liquid-phase bonding technique.The effect of bonding temperature on the microstructures and strengths of the joints was investigated.The results showed that gradient structural multiple interlayers composed of ‘‘C–Ti reaction layer/Ti–Ni intermetallic compound layer/Ni–Cu sosoloid/residual Cu layer/Ni-GH3044 diffusion layer' were formed between C/C composite and GH3044.The shear strength of the C/C composite/GH3044 joint reached the highest value of 26.1 MPa when the bonding temperature was 1,030 °C.In addition,the fracture morphology showed that the fracture mode changed with the increase of bonding temperature.     

New Type Gold Bonding Wire

ＮｅｗＴｙｐｅＧｏｌｄＢｏｎｄｉｎｇＷｉｒｅＧａｏＲｕｉ，ＪｉａｎｇＸｕａｎ，ＬｕＢａｏｇｕｏａｎｄＢａｎＬｉｚｈｉ（高瑞）（江轩）（吕保国）（班立志）（ＧｅｎｅｒａｌＲｅｓｅａｒｃｈＩｎｓｔｉｔｕｔｅｆｏｒＮｏｎ－ｆｅｒｒｏｕｓＭｅｔａｌｓ，Ｂｅｉ...     

Energy Density Dependence of Bonding Characteristics of Selective Laser-Melted Nb–Si-Based Alloy on Titanium Substrate

Spherical Nb–20Si–24Ti–2Cr–2Al pre-alloyed powders were processed by selective laser melting(SLM) on Ti6Al4V substrates with different energy densities. A series of single tracks and single layers were produced using different processing parameters, including powder size, laser power, scanning speed and hatch distance. Results showed that the pre-alloyed powders ranging from 45 to 75 lm were more applicable to SLM with less balling tendency, in comparison with those between 75 and 180 lm. The increase in linear energy density(LED) resulted in the decrease in contact angle and the increase in the width of single track as well as its penetration depth into the substrate. Smaller hatch distance leaded to a larger remelted part of the former track and a higher volumetric laser energy density. With a thickness of 75.6 lm, an interfacial intermediate layer, enriched in Ti and depleted in Nb, Si, Cr and Al, was formed between the SLM part and the Ti6Al4V substrate. The mechanisms of the elimination of balling phenomenon by employing a higher LED and the interfacial bonding characteristics between Nb–Si-based alloys via SLM and the Ti6Al4V substrate were discussed.     

Analysis of Chemical Bonding and Structural Network of Gold Silicide in Core–Shell Silicon Nanowire

The Au-catalyzed core–shell silicon nanowires (Si-NWs) were synthesized by chemical vapor deposition by using SiH₄ and H₂ precursor gases. The TEM and FTIR studies revealed that the Si-NWs consist of core silicon surrounded by a thick oxide sheath and Au distributed at the a-SiOx/Si interface. The x-ray photoelectron spectroscopy (XPS) was used to study the chemical composition and electronic environments of gold silicide in the a-SiO _x /Si-NWs. The elemental analysis and chemical network of gold silicide of core–shell Si-NWs were explained on the basis of the random atomic distribution of Si, O and Au atoms. The Raman spectra and XRD peak reveal the crystalline core of Si-NWs. The individual contribution to the Au (4d) core orbital was deconvoluted to Au-Si-Au, Au-Si-O, Au-Au, Au-O-Au, Au-O-Si and Au=O/Au-O₂ bonding structure. The analysis shows that the O linked with Si and Au has also contributed to growth of Si-NWs.     

The Effect of Ti on Microstructural Characteristics and Reaction Mechanism in Bonding of Al-Ceramic Composite

The effect of Ti on microstructural characteristics and reaction mechanism in bonding of Al-Ceramic composite was studied. Ti and Al-Ceramic composite were diffusion welded at 550, 600, 700, 800, and 900 °C in a vacuum furnace. The microstructures and compositions of the interface layers were analyzed, and the mechanical properties and fracture morphology of the joints were examined. The results indicated that there was a systematic switch from Ti/Ti₇Al₅Si₁₂/composite at 600 °C and Ti/TiAl₃/Ti₇Al₅Si₁₂/composite at 700 °C to Ti/Ti₇Al₅Si₁₂/TiAl₃/Ti₇Al₅Si₁₂/composite at 800 °C and Ti/Ti₇Al₅Si₁₂/TiAl₃/composite at 900 °C. The formation of TiAl₃ at 700 and 800 °C depended on Al segregation, which was an uphill diffusion driven by chemical potential. The maximum shear strength was 40.9 MPa, found in the joint welded at 700 °C. Most joints fractured between Ti₇Al₅Si₁₂ and Al-Ceramic composite. In any case, Ti₇Al₅Si₁₂ was favorable for Al-Ceramic composite welding, which attached to Al-Ceramic composite, reducing the differences in physiochemical properties between SiC and metal, improving the mechanical properties of the joints and increasing the surface wettability of Al-Ceramic composite.     

‘Road map’ of the development of the technological component of the strategy of national security

This article is devoted to the development of guidelines for road mapping in planning the development of the technological component of structures of national security. Making the ‘road map’ is reduced to the method of conventional optimization i.e. achievement of the target in conditions of severe limitations of existing resources taking into account the effect of controlled and uncontrolled factors. Such a result can be regarded as a scientific novelty.     

Bonding of Al2O3 ceramic and Nb using transient liquid phase brazing

The brazing of Al2O3 to Nb was achieved by the method of transient liquid phase (TLP) bonding. Ti foil and Ni-5V alloy foil were used as interlayers for the bonding. The base materials were brazed at 1423-1573 K for 1-120 min. The results show that the shear strength of the joint first increases and then decreases with increasing holding time and brazing temperature. The joint interface microstructure and elements distribution were investigated. It can be concluded that a composite structure, in which the base metals are solid solution Nb(V) and Nb(Ti) reinforced by Ni3Ti, is formed when the brazing temperature is 1473 K and holding time 15 min, and a satisfactory joint strength can be achieved. The interaction of Ti foil and Ni-5V foil leads to the formation of liquid eutectic phase with low melting point, at the same time the combination of Ti come from the interlayer with O atoms from Al2O3 results in the bonding of Al2O3 and Nb.     

New Technique for Making Composite Materials—Field Assisted Diffusion Bonding of Alumina to Aluminum

1. Introduction There are two ways to join ceramics tometals: brazing and bonding. The brazing in-cludes Moly- Manganese Process, ActiveSubstrate Process (Ti- coating on theceramic) and Active Filler Metal Process(Active Brazing Filler Metal). However, thedisadvantage of the Moly-Manganese Processis time-comsuming and energy-comsuming.And the active brazing is limited by the low     

Influence of the configuration of pin on the quality of plastics FSW joints

An investigation on the quality of PVC joints welded by friction stir welding （ FSW ） with different shape of pin was carried out. The results show that when the rotating speed of stir tool is 1 660 r/min and the welding speed is 25 mm/min, the beads welded with upright taper pin are plump and joined well, the average tensile strength of which is 19. 1 MPa （the maximum is 20. 3 MPa）, being 49. 2% of that of parent material. The beads welded with cylindrical pin are also joined rather well plump and smooth, the average tensile strength of which is 17. 6 MPa, being 45.3% of that of parent material. The beads welded with inverted taper and cylindrical screw pin are only partially joined or disjoined. The optimum welding temperature range of PVC is 180 - 190℃. If the temperature beyond 200℃ the material will be burnt. If the temperature is under 170℃ the material will be joined partially or disjoined.     

Influence of the rotation frequency of the magnetic field on the dynamics of the domain structure of thin Fe–3% Si crystals

Some specific features of the reconstruction of the domain structure of thin (0.10 mm) Fe–3% Si single crystals have been investigated depending on the frequency of the magnetization reversal in rotating magnetic fields. The studies have been carried out in the range of frequencies of 60–300 Hz and induction amplitudes of 0.5–1.6 T. It has been established that the magnetization reversal of the samples of this thickness occurs via the displacements of 180° domain walls of the stripe domain structure without the participation of the C-domain walls. A qualitative explanation to the revealed features of the behavior of the domain structure has been given, and their possible contribution to the magnetic losses of the investigated samples has been evaluated.     

Recrystallization and the possibility of the realization of the α-γ diffusionless transformation during the ultrarapid laser heating of steels

Analysis is given of phase and structural transformations occurring upon ultrarapid laser heating in steels with different initial structures, namely, after annealing, after preliminary quenching, quenching and tempering, and after quenching with subsequent deformation and tempering. It is shown that a significant suppression of diffusion processes occurs during laser heating; this circumstance substantially affects the nature of the phase and structural transformations proceeding during laser processing. Special attention is given to studying the process of recrystallization and to the phenomenon of structural heredity during laser heating. The process of recrystallization during laser heating is considered as consisting of two stages, namely, an ordered lattice rearrangement (α-γ transformation) and the recrystallization of austenite that suffered phase-transformation-induced hardening (“phase naklep”). The effect of tempering and plastic deformation on the recrystallization of a preliminarily quenched steel consists in the intensification of the second stage, i.e., of the recrystallization of the transformation-hardened austenite. It is shown that the α-γ transformation during the laser heating of steels with the initial structure of lath martensite occurs by the “mechanism of recovery,” i.e., via the formation and growth of austenite nuclei. In steels with the initial structure of pearlite, the nucleation of austenite during laser heating can occur by a shear martensite-like diffusionless mechanism with the observance of characteristic orientation relationships between the initial ferrite and the newly formed austenite.     

Influence of the Iron Anisothermal Sintering on the Characteristic of the Hollow Cathode Discharge

SINTERING of steels and ceramics is conventionallycarried out in a furnace in a controlled atmosphere.Several alternative techniques have been developedsince 1966, as mentioned by Johnson et al. [1], toobtain components with improved properties, resultingin new applications for powder technology. Plasmasgenerated in microwave cavities, in hollow cathodedevices and microwave or RF-inductively coupleddischarges have all been used for sintering ceramics[2-5]. In the above mentioned papers it …     

Research for the method of image acquisition of the molten pool in the TIG welding of aluminum alloy

Obtaining the image of molten pool aluminum alloy‘ s tungsten inert gas (TIG) welding becomes a challenging problem in the welding field. In this paper, a bran-new optical sensor based analyzing the light spectrum was designed, and the clear image of the molten pool during the aluminum alloy‘ s welding using the common industrial CCD camera was obtained. And with the new algorithm provided by myself, the desirable characteristic parameters of the molten pool of aluminum alloy‘ s welding were obtained, and it provides a good base for advanced monitor welding quality.     

Effect of Annealing on the Magnetism of the Sintered NdFeB Magnet

This paper deals with the effect of annealing on the magnetism of the sintered NdFeB magnet with a composition of Nd30B5.1Dy1.2Al0.6Nb0.7Fe62.4. Microstructural investigations of the grain size and grain boundaries with SEM were carried out. Microstructural investigations showed the presence of some Nd-rich phase in grain boundaries and main phase.The results of magnetic properties analysis shows that this non-magnetic Nd-rich phase, produced in annealing process,can increase or decrease the magnetism of the sintered NdFeB-type permanent magnet. Appropriate amount of Nd-rich phase will strengthen the pinning field and elevated the coercive force of magnet, but too many these non-magnetism phases in Nd2Fe14B main phase will decrease it. When the sintered NdFeB magnet was annealed at 3Pa and 492℃ for an hour the coercive force would raise from 915.6kA/m to l164.SkA/m, and the (BH)max from 277.7kJ/m to 349.5kJ/m. However, annealing at a non-optimized temperature at 542℃, microstructure changes in some main phase will leading the decrease of properties.     

Electrochemical and Reaction Bonding Processing of Thick ZrO_2/Al_2O_3 Composite Coatings

CERAMIC coatings are currently of much interest forapplications in high-temperature and highly corrosiveenvironments.Formation of ceramic coatings byelectrochemical processing is a relatively newtechnique.'1'It presents several advantages overalternative coating techniques.'2'Recently wedeveloped a novel fabrication technique for theproduction of ceramic/ceramic and metal/ceramiccomposite coatings by electrochemical processing.'31The technique combined two electrochemicaldeposition methods,…     

Effect of the structure of the oxidized titanium surface on the particle size and properties of the deposited copper–molybdate catalyst

The parameters of wetting of oxide coatings on titanium formed by the method of plasma electrolytic oxidation (PEO) in an aqueous silicate electrolyte with subsequent deposition of a layer of TiO₂ nanoparticles and ultrasonic treatment by a polymer–salt gel including copper and molybdenum compounds have been investigated. The effect of the oxidized surface microrelief, TiO₂ nanoparticle layer, and pore shape and size on impregnation solution spreading and the structure of the copper–molybdenum catalytic coating formed at further thermal treatment has been demonstrated. Complex oxide composites with ultradispersed catalyst particle sizes characterized with high activity in oxidation of carbon black particles have been obtained.     

Bonding Character and Formation Energy of Point Defects of He and Vacancy on （001） Surface of bcc Iron by First Principle Calculations

The structure and energy of He impurities and vacancy on (001) surface of bcc iron are investigated by an ab initio method. Three cases for stabilities of a He atom at the surface are found: some of He atoms at surface atomic layers (SAL) relax into vacuum gap; some of surface He atoms at octahedral interstitial site relax into more stable tetrahedral interstitial site; some of surface He atoms still stay at tetrahedral interstitial site. The un-stability of the He atom at the surface system can be explained by deformation mechanism of charge densities and electronic densities of states. It is found that formation energy of the point defects from the topmost SAL to bulk-like atomic layer increase gradually, for example, the formation energies of a monovacancy at the first five topmost SALs are equal to 0.33, 1.56, 2.04, 2.02 and 2.11 eV, respectively. The magnetic moments of Fe atoms in the surface atomic layers are also calculated.