Progress in Joining Ceramics to Metals

The research and development of joining methods of ceramics to metals, especially brazing, diffusion bonding and partial transition liquid phase bonding, were introduced. Some opinions were put forward. For new composites emerging, it is necessary to develop new joining methods, particularly in the field of high temperature technique for joining ceramics to superalloys.

Joining mechanism of field-assisted diffusion bonding of solid electrolyte ceramic to metals

Field assisted diffusion bonding applied in the joining of solid electrolyte borosilicate glass, β ″ Al 2O 3, Y 2O ZrO 2 to monocrystal silicate and aluminum were proceeded with bonding machine in the assistance of static electric field. TEM, SEM, XRD and other means were applied to investigate and analyze microstructure of interface. It is supposed that the interfacial area is a model of metal oxides ceramic, and the joining mechanism is solid diffusion joining and static electric bonding. The process of ions migration and accumulation under electric field is the most essential factor for the anodic oxidation and interfacial joining. Temperature and voltage are the basic factors of the solid diffusion bonding of interfacial oxidation. And voltage, temperature, pressure and the condition of surface are the most important factors that govern the bonding process.

Atomically bonding Na anodes with metallized ceramic electrolytes by ultrasound welding for high-energy/power solid-state sodium metal batteries

A solid-state sodium metal battery has cut a striking figure in next-generation large-scale energy storage technology on account of high safety,high energy density,and low cost.Nevertheless,the large interfacial resistance and sodium dendrite growth originating from the poor interface contact seriously hinder its practical application.Herein,a modified ultrasound welding was proposed to atomically bond Na anodes and Au-metalized Na_(3)Zr_(2)Si_(2)PO_(12) electrolytes associated with the in situ formation of Na–Au alloy interlayers.Thereupon,intimate Na_(3)Zr_(2)Si_(2)PO_(12)-Au/Na interfaces with a low interfacial resistance(~23Ωcm^(2))and a strong dendrite inhibition ability were constructed.The optimized Na symmetric battery can cycle steadily for more than 900 h at 0.3 mA cm^(-2) under a low overpotential(<50 mV)of Na electroplating/stripping and deliver a high critical current density of 0.8 mAcm^(-2) at room temperature.By incorporating the above interface into the solid-state Na metal battery,taking three-dimensional Na_(3)V_(2)(PO_(4))_(3) as the cathode,the full battery offers a high energy density of 291 Wh kg^(-1) at a high power density of 1860Wkg^(-1).A pouch-type solid-state sodium metal full battery based on a ceramic electrolyte was assembled for the first time,and it lit a 3 V LED lamp.Such a strategy of the ultrasound welding metalized solid-state electrolyte/Na interface by engineering the Na-Au interlayer would pave a new pathway to engineer a low-resistance and highly stable interface for high-energy/density solid-state sodium metal batteries.

MICROWAVE JOINING OF ALUMINA CERAMIC AND HYDROXYLAPATITE BIOCERAMIC

Microwave joining is a rapid developmental new technique in recent years. This paper introduces a new microwave joining equipment which was made by our lab, succeeds in alumina ceramic - hydroxylapatite bioceramic join in the equipment, and analyzes the join situation of join boundary by using scanning electron microscope (SEM), this paper analyzes the mechanism of microwave joining also. (Author abstract) 4 Refs.

Microstructure and properties of the joints of ZrO2 ceramic/ stainless steel brazed in vacuum with AgCuTi active filler metal

The ZrO2 ceranfic was successfully jointed to stainless steel by vacuum brazing with active filler metal. The AgCuTi active filler metal was used and the joining was performed at a temperature of 850 ℃ for 10 rain. The microstructures of the joints were characterized by metallographic microscopy, scanning electron microscopy （SEM）, and energy dispersive spectroscopy （EDS）. Metallographic microscopy analysis shows that the morphology of the cross section was a sandwich structure and the TiO is observed in the surface of ZrO2/ stainless steel. The diffusion and enrichment of the elements are the key roles in the brazing of ZrO2 ceramic and stainless steel. The formation of TiCu compounds inhibited the further diffusion of titanium into stainless steel or the ZrO2 ceramic to form TiO compound. In the experimental conditions, the average tensile strength is 80MPa for the joint of ZrO2 ceramic / AgCuTi/ stainless steel systems. A complete joint is formed between the ZrO2 ceramic and stainless steel with the leakage rate at the degree of 10 ^-12 Pa · m^3/s.

Green State Joining of ZrO_2(8YSZ)-Al_2O_3 Ceramics Using Slurry Containing PLS Nanocomposites

Joining of ZrO_2 (containing 8% (mol fraction) Y_2O_3,as the composition used in oxygen sensors) to 95Al_2O_3 (widely used at elevated temperature) in green state was described using polymer/layered silicate (PLS) nanocomposites contained slurry,without applied pressure. Microstructure of the joined section was investigated. The effects of interlayer and PLS on joining qualities were analysed. The results show that interface cracks are easily produced because of mismatch of both thermal expansion and/or sintering shrinkage between joined samples. With an optimized condition of joining layer composition and solid contents,a fine joint could be obtained without obvious cracks,pores and other defects. This process is suitable for joining of various kinds of advanced ceramics.

Direct Comparison between Tensile Strength and Flexural Strength of Ceramic/Metal Brazing Joint

A design of the sandwich joint,steel/ ceramic/steel,was made for direct comparison be- tween tensile and flexural strength of ceramic/metal joint.The flexural strength is about twice as high as the tensile strength for the same joint.The results also showed that the flexural test is more excellent than tensile test for joint with a high interracial bond strength.

MICROSTRUCTURE AND INFRARED EMISSIVITY AT NORMAL TEMPERATURE IN TRANSITIONAL METAL OXIDES SYSTEM CERAMICS

The fabrication of Fe2O3-MnO2-Co2O3-CuO system ceramics, and the composite system ceramics of transitional metal oxides-cordierite and transitional metal oxides-kaolinit are presented in this work. The research was carried out with the main attention to the infrared emissivity in the band of 8 similar to 14 mu m at room temperature, the microstructure of the ceramics and the relation between them. High infrared emissivities exceeding 0.9 in the band of 8 similar to 14 mu m at room temperature were gained in the transitional metal oxide ceramics and the composite system ceramics. It is suggested that the formation of inverse spinels and partially inverse spinels, such as Fe3O4, CoFe2O4, CuFe2O4 and CuMn2O4, is beneficial to the enhancement of the infrared emissivity of the transitional metal oxide ceramics. The transitional metal oxides play an important role in determining the infrared emissivity of the composite system ceramics.

Fabrication and Life Prediction of SSiC Ceramic Joint Joined with Silicon Resin YR3370

Joints between sintered silicon carbide （SSiC） were produced using a polysiloxane silicon resin YR3370 （GE Toshiba Silicones） as joining material. Samples were heat treated in a 99.99% nitrogen flux at temperatures ranging from 1 100 ℃ to 1 300 ℃. Three point bending strength of the joint reached the maximum of 179 MPa as joined at 1 200℃. The joining layer is continuous, homogeneous and densified and has a thickness of 2 μm -5μm. The joining mechanism is that the amorphous silicon oxycarbide （SixOyCz） ceramic pyrolyzed from silicon resin YR3370 acts as an inorganic adhesive to SSiC substrate, which means the formation of the continuous Si-C bond structure between SixOyCz structure and SSiC substrate. Life prediction of the ceramic joint can be realized through the measurement of the critical time of the joint after the cyclic loading test.

Lithiated Nafion-garnet ceramic composite electrolyte membrane for solid-state lithium metal battery

Single-ion conducting solid polymer electrolytes are expected to play a vital role in the realization of solid-state Li metal batteries.In this work,a lithiated Nafion(Li-Nafion)-garnet ceramic Li6.25La3 Zr2 Al0.25O12(LLZAO)composite solid electrolyte(CSE)membrane with 30μm thickness was prepared for the first time.By employing X-ray photoelectron spectroscopy and transmission electron microscope,the interaction between LLZAO and Li-Nafion was investigated.It is found that the LLZAO interacts with the Li-Nafion to form a space charge layer at the interface between LLZAO and Li-Nafion.The space charge layer reduces the migration barrier of Li-ions and improves the ionic conductivity of the CSE membrane.The CSE membrane containing 10 wt%LLZAO exhibits the highest ionic conductivity of2.26×10-4 S cm-1 at 30℃among the pristine Li-Nafion membrane,the membrane containing 5 wt%,20 wt%,and 30 wt%LLZAO,respectively.It also exhibits a high Li-ion transference number of 0.92,and a broader electrochemical window of 0-+4.8 V vs.Li+/Li than that of 0-+4.0 V vs.Li+/Li for the pristine Li-Nafion membrane.It is observed that the CSE membrane not only inhibits the growth of Li dendrites but also keeps excellent electrochemical stability with the Li electrode.Benefitting from the above merits,the solid-state LiFePO4/Li cell fabricated with the CSE membrane was practically charged and discharged at 30℃.The cell exhibits an initial reversible discharge specific capacity of 160 mAh g-1 with 97%capacity retention after 100 cycles at 0.2 C,and maintains discharge specific capacity of 126 mAh g-1 after500 cycles at 1 C.The CSE membrane prepared with Li-Nafion and LLZAO is proved to be a promising solid electrolyte for advanced solid-state Li metal batteries.

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.

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.

Kinematics Analysis and Optimization of the Fast Shearing-extrusion Joining Mechanism for Solid-state Metal

Dynamical Joining of the solid-state metal is the key technology to realize endless hot rolling. The heating and laser welding method both require long joining time. Based on super deformation method, a 7-bar and 2-slider mechanism was developed in Japan, and the joining time is less than 0.5 s, however the length of each bar are not reported and this mechanism is complex. A relatively simple 6-bar and 1-slider mechanism is put forward, which can realize the shearing and extrusion motion of the top and bottom blades with a speed approximately equal to the speed of the metal plates. In order to study the kinematics property of the double blades, based on complex vector method, the multi-rigid-body model is built, and the displacement and speed functions of the double blades, the joining time and joining thickness are deduced, the kinematics analysis shows that the initial parameters can＇t satisfy the joining process. Hence, optimization of this mechanism is employed using genetic algorithm（GA） and the optimization parameters of this mechanism are obtained, the kinematics analysis show that the joining time is less than 0.1 s, the joining thickness is more than 80% of the thickness of the solid-state metal, and the horizontal speeds of the blades are improved. A new mechanism is provided for the joining of the solid-state metal and a foundation is laid for the design of the device.

Identification and evolution of interfacial structure of SiO2 glass ceramic/Ti-6AI-4V alloy joint bonded with AgCu/Ni interlayer

AgCu/Ni composite interlayer was utilized to join SiO2 glass ceramic （74. 52% SiO2-23. 40% Al2 03 -2. 08 % K2 O, wt. % ） and Ti-6Al-4V alloy by eutectic reaction. Interface structures of the joints were identified by means of TEM analysis. This joining method contains three characteristic processes, which are the melting of AgCu eutectic alloy, eutectic reaction between interlayer and Ti-6Al-4V base material and active reaction of element Ti to SiO2 glass ceramic. It is different from traditional active brazing because active element Ti totally dissolves from Ti-6Al-4 V and reacts with SiO2 glass ceramic. SiO2 glass ceramic can be joined suecessfuUy to Ti-6Al-4 V alloy by this novel bonding method and the joint exhibits high shear strength, up to 110 MPa.

FEM simulation on residual stress distribution during diffusion bonding between Ti （ C, N） metallic ceramic/interlayer/40Cr steel

Based on ANSYS FEM software, the distribution of residual stress in the diffusion bonding joints between Ti（ C,N） metallic ceramic/interlayer/4OCr steel was calculated and experimentally ver^ed. The results showed that the trend on the distribution of residual stress field in the joints was not changed with the use of interlayer. The maximum residual stress was always located in metallic ceramic with area ranging from 1 mm to 4 mm to the interlayer. The maximum residual stress in the joints was also affected by diffusion temperature. The satellite pulse current during the initial stage on diffusion bonding can promote the formation of liquid film at the interface, by which diffusion temperature and loading pressure can be greatly decreased. The crack initiation was easily produced at the corner of Ti （ C, N） metallic ceramic close to the interlayer. If a higher residual stress produced in the joints, the crack was propagated into the whole ceramic.

Reactive synthesis Ti （CN） -based metal ceramic coating by electric-spark deposition

Electric-spark deposition （ESD） was adopted for depositing a Ti（ CN） -based ceramic coating on the TC4 titanium alloy substrate using a laboratory-developed electric-spark deposition system, a nitrogen-sealed atmosphere and graphite electrode. The surface morphology, microstructure, interfacial behavior between the coatings and substrate, phase and element composition of the coatings were investigated by scanning electron microscope （ SEM ） , X-ray diffraction （ XRD ） , X-ray photoelectron spectroscopy （ XPS ） and Auger electron spectroscopy （ AES ） . Microhardness profile was measured with a Vickers microhardness tester. The results show that metallurgical bond between the coating and substrate is realized and the phase of coatings are made up of Ti（ CN ） spherocrystal and dendritic crystal, TiV and C. Ti（ CN） ceramic particles, which is in-situ synthesized by the reaction among titanium from the substrate, carbon from the graphite electrode and nitrogen from the shielding nitrogen gas, is about 600 mn and distributes dispersively among the coatings. Microharduess profile falls off with the coatings thickness increasing and the highest microhardness values of the superficial coating could be up to 1 496HV, which is six times more than that of the substrate.

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.

Synthesis of Ceramic Tiles Reinforced with Addition of Aluminum Particulate Waste

Research conducted on ceramic materials has been investigating the incorporation of solid waste into their formulations,driven by the proper disposal of such waste and the reduction of negative environmental impacts.This study analyzed the effects of adding aluminum powder residue to the physical properties of ceramic masses with the aim of obtaining new formulations for ceramic tiles.The aluminum residue and the standard mass for ceramic tile production were chemically characterized and homogenized to obtain new formulations with the incorporation of 4%,6%,8%,and 10%aluminum powder in the ceramic mass.The specimens were uniaxially pressed and sintered at a temperature of 1,200°C for 2 h,undergoing three different temperatures(100°C,400°C,and 650°C)for 30 min each.They were evaluated for WA(water absorption),RLq(linear shrinkage),SEM(scanning electron microscopy),and TRF(flexural strength)modulus.The results demonstrate that the addition of aluminum powder residue is feasible in the proposed formulations(4%,6%,8%,and 10%),as they enhance the mechanical properties of the ceramics compared to the formulation with 0%residue,at a sintering temperature of 1,200°C.

ANALYTICAL MODEL OF CERAMIC/METAL ARMOR IMPACTED BY DEFORMABLE PROJECTILE

A new analytical model was established to describe the complex behavior of ceramic/metal armor under impact of deformable projectile by assuming some hypotheses. Three aspects were taken into account： the mushrooming deformation of the projectile, the fragment of ceramic tile and the formation and change of ceramic conoid and the deformation of the metal backup plate. Solving the set of equations, all the variables were obtained for the different impact velocities： the extent and particle velocity in rigid zone; the extent, cross-section area and particle velocity in plastic zone; the velocity and depth of penetration of projectile to the target; the reduction in volume and compressive strength of the fractured ceramic conoid; the displacement and movement velocity of the effective zone of backup plate. Agreement observed among analytical result, numerical simulation and experimental result confirms the validity of the model, suggesting the model developed can be a useful tool for ceramic/metal armor design.

Research on the Formation of Metal-Ceramic Surface Composite Coating by Wide-Band Laser Cladding

Large-area in-situ synthesized TiB2(TiB, Fe2B)—Fe metal-ceramic composite coating has been fabricated on medium carbon steel by laser cladding with the optimal laser parameters and overlapping coefficient. The bonding interfaces between the cladding layer and the matrix and among different tracks are excellent. Microanalysis on the cladding layer shows that the morphology is a little different from each other and the element distribution and the mechanical properties are unanimous in each track while the mechanical property of the cladding layer shows a gradual change from the surface to the matrix. The in-situ separating out thin ceramic phases in the coating contribute to the improving of its properties greatly.