Ti Filler Research Articles

The abrasion resistance of brazed diamond using Cu–Sn–Ti composite alloys reinforced with boron carbide

Cu–Sn–Ti filler is commonly used in industrial production to prepare diamond tools. However, the hardness and strength of the Cu-based brazing filler metal are low, resulting in poor wear resistance of the brazing filler metal. In this work, novel brazed diamond segments were fabricated using Cu-Sn-Ti-xB4C composite fillers. The correlation between the interfacial compounds and friction and wear performance was studied. The results showed that after adding B4C with 2 wt%, B4C can react with the Cu-Sn-Ti filler, which moderates the wetting reaction between the active alloy and the diamond particles during brazing. The exposure of diamond was high and no obvious thermal damage occurred. The layered compounds is formed on the interface of the diamond; the SEM and XRD characterization prove that the compounds generated on the diamond surface is TiC. Vickers hardness tester was used to measure the microhardness of the fillers layer and the interface layer, and the hardness value of the filler layer gradually increased with the increase of B4C content. When the addition of B4C is 2%, the hardness value of the interfacial layer reaches 255 HV0.05. The friction and wear experiments results showed that when B4C was added at 2%, the wear material removal was 0.189 g and the wear resistance of the brazed specimens was optimal.

Microstructure and Properties of Wc–Co Cemented Carbide/40cr Steel Joints Brazed at Low–Temperature with Ag–Cu–In–Ti Filler Alloy

Microstructure and Properties of Wc–Co Cemented Carbide/40cr Steel Joints Brazed at Low–Temperature with Ag–Cu–In–Ti Filler Alloy

Study on water absorption and mechanical properties of CNF–Ti reinforced epoxy resin composites

ABSTRACT The effects of carbon nanofibres (CNFs), titanium nanoparticles (Ti) and CNF–Ti fillers on the water absorption and mechanical properties of the composites were studied. The results showed that with the increase in filler mass fraction, the water absorption and mechanical properties of epoxy resin composites showed a trend of first increasing and then decreasing. When 6% CNF–Ti filler was added, the water absorption and diffusion coefficients of the composites were reduced to 2.32% and 1.04 ± 0.05 × 10−6 m2/s, and their tensile and impact strengths were improved by 200% and 124.55%, respectively, compared with the pure resin. However, when the filler was added in excess, agglomerates were generated inside the composite, which can affect the performance of the composite to a great extent. The above experimental results were verified by morphology observations via scanning electron microscopy.

Effects of Ga on Mechanical Properties and Microstructure of Cu–Sn–Ti Filler

To solve a series of problems of Cu–Sn–Ti fillers, Ga is added to the fillers to promote its mechanical properties and microstructure. The metallographic structure of Cu–Sn–Ti–xGa filler metals is detected by optical microscope. Energy dispersive spectroscopy (EDS) areal, X‐ray diffraction (XRD), and differential thermal analysis (DSC) are used to analyze the morphology and microstructure of the fillers. The results show that doped Ga can significantly decrease the melting point and increase mechanical properties of the fillers. The shear strength of the filler metals with 1% Ga content is 160% higher than without Ga. In addition, it is also observed that a small amount of Ga refine the CuSnTi filler metals matrix structure. The diffusion of elements in the filler metals is detected. Compared with Sn solid solution, Ga tends to form a solid solution with Cu. When the Ga content is 2 wt%, the shear strength of the filler metal decreases due to the appearance of coarse crystals at the bottom of the dimple. Through the study of the reaction layer between diamond and filler metal, it is found that Ga can increase the thickness of the interface reaction layer.

Effect of single alloying element (Ti, Nb, V, Cu) on microstructure and mechanical properties of dissimilar TiAl/Ni-based superalloy laser joints

Dissimilar welding of TiAl-based alloy and Ni-based superalloy with different single alloying element (Ti, Nb, V, Cu) was performed by laser. Detailed effects of alloying element on microstructural characterization and mechanical properties of the joints were investigated. The results showed that laser welding of TiAl/Ni-based superalloy was not achieved by using Ti filler metal. The large number of Ni0.35Al0.30Ti0.35 brittle phases in the joint was the main factor of affecting the weldability of joint. Laser welding was not achieved a better connection by using Nb filler metal, and macrocracks existed in the weld, which mainly attributed to the formation of AlNbNi, AlNbNi2 and Cr2Nb intermetallics. The dissimilar metals was successfully welded by using V filler metal, and (V,Cr) solid solution and (V,Cr)/AlNi2Ti eutectic phase were formed in the weld zone. The average tensile strength of the joint was 140 MPa and the joint fracture occurred on Ni-based superalloy side, owing to the fine (V,Cr)/AlNi2Ti eutectic phase. The dissimilar metals was successfully welded by using Cu filler metal, and Cu solid solution and Al(Ni,Cu)2Ti/Cr eutectic phase were formed in the weld zone. The average tensile strength of the joint was 155 MPa and the joint fracture occurred on TiAl alloy side where more AlCuTi and AlCu2Ti formation has.

Improved mechanical strength of the C/C–Mo joints by introducing MoNiSi ternary compounds as the main phase of the interlayer

In order to improve the mechanical performance of the C/C–Mo joint, MoNiSi ternary compounds were designed as the main phase of the interlayer. Utilizing NiCrSi–Ti as the braze filler, these compounds were formed and uniformly distributed in the C/C–Mo joint at 1330 °C without any pressure. As MoNiSi was introduced to the joint, its shear strength is up to 46.10 MPa, which is 29% higher than the joint without MoNiSi brazed with NiCr–Ti filler. MoNiSi ternary compounds restrain the formation of the brittle binary silicides, and the uniform interlayer with MoNiSi and Ni-based solid solution reduces the residual thermal stress in the joint via plastic deformation, avoiding the formation of defects. Furthermore, the existence of residual Si is beneficial to the formation of a Ni-based reaction layer at the C/C side, resulting in a strong bonding between C/C composites and braze. The MoNiSi with a high hardness would result in the deflection of crack, consuming more energy, which plays a positive role in the bonding performance of the C/C–Mo joint.

Wetting behavior of AgCu-4.5Ti filler reinforced by carbon nanotubes on C/C composite

The effect of Carbon Nanotubes (CNTs) content on the wettability of AgCu-4.5Ti + x CNTs (wt%) composite filler alloys on C/C composite was investigated. The results show that the added CNTs reacted with element Ti in the filler and produced the dispersed fine in situ synthesized TiC particles, which increased the consumption of element Ti and provided the nucleus for the growth of Ti-Cu compounds simultaneously. The above effects of introducing CNTs, inhibited the formation of Ti-Cu compounds, also changed the distribution of compounds, which dramatically influenced the interfacial microstructure and characteristics of wetting behavior. The increase of CNTs content refined and dispersed coarse Ti-Cu compounds, decreased the initial spreading temperature, and improved the wettability, but high content of CNTs (more than 0.3wt%) decreased the wettability of the filler alloy. The wetting interfacial microstructure of corresponding composite filler alloys were analyzed by Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectrometer (EDS) and Transmission Electron Microscope (TEM), which consisted of TiC, TiCu, TiCu2 and TiCu4 compound. The typical wetting behavior of AgCu-4.5Ti + 0.3wt% CNTs composite filler on C/C composite was divided into four stages. The effect mechanism of CNTs content on the wetting behavior was proposed.

Investigation on wetting behavior and mechanism of AgCu-Xwt.%Ti filler metal/AlN ceramic reactive wetting system: Experiments and first-principles calculations

Abstract The wetting behavior and mechanism of AgCu-Xwt.%Ti filler metal on AlN ceramic were investigated using experiments and first-principles calculations. The results indicate that the interfacial ideal adhesion work of wetting interface after interfacial chemical reaction is a crucial factor influencing the wettability of AgCu-Xwt.%Ti/AlN wetting system. This factor is controlled by the interfacial bonding characteristic. AgCu/AlN ceramic is a non-reactive wetting system, which has poor wettability with a contact angle of 22.9°. When 1.5 wt.% of active element [Ti] is added in AgCuTi filler metal, interfacial chemical reaction occurs, producing TiN. Therefore, the wetting interface is composed of AgCu-1.5wt.%Ti filler metal after chemical reaction and TiN (ACTi-1/TiN interface), which exhibits a large interfacial ideal adhesion work of 9.908 J/m2, leading to a small contact angle of 11.7°. When Ti content increases to 3.0 wt.%, the ionic bonding strength of wetting interface, composed by AgCu-3.0wt.%Ti filler metal after chemical reaction and TiN (ACTi-2/TiN interface), becomes stronger than that of ACTi-1/TiN interface owing to the increasing residual Ti content. Consequently, the interfacial ideal adhesion work further increases to 9.711 J/m2, and a decreasing contact angle of 8.2° is achieved. However, when Ti content reaches to 4.5 wt.%, although residual Ti content in AgCu-4.5wt.%Ti filler metal after chemical reaction (ACTi-3) is further increased, both covalent and ionic bonding strengths of ACTi-3/TiN interface are closer to those of ACTi-2/TiN interface. This leads to an almost unchanged interfacial ideal adhesion work and contact angle of 9.753 J/m2 and 8.1°, respectively.

Comparative study between furnace brazing and laser brazing

Nowadays, brazing has been widely used in many industries, especially in the automotive application. The brazing process is introduced as it can be used to join the different metals together without melting the parent material. In this present study, furnace brazing and laser brazing of Ti-6Al- 4V titanium alloy and 316 L stainless steel (SS) with silver-based, BAg 8-1.5Ti filler metal were studied. There are significantly different between furnace brazing, also known as conventional brazing method and laser brazing in terms of joining strength and microstructure reaction. Furnace brazing was performed at 870°C and 880°C with 30 minutes of heating duration. Meanwhile, laser brazing was performed using a 200Watt continuous wave laser with varying laser power. Both of brazing method was conducted with a vacuum pressure of 3×10−3 Pa. Besides, to maintain the accuracy of the temperature measurement of laser brazing, an infrared thermometer is used. The tensile test was conducted to analyse the mechanical properties. The cross-sections of the brazed joints have been examined using an optical microscope. The brazed joints of the furnace brazing show an average tensile strength of 55.89 kPa for 880°C and 43.16 kPa for 870°C. Nonetheless, the maximum tensile strength of laser brazed joints was 27.95 kPa, which is lower than furnace brazed joints.

Promoting the bonding strength and abrasion resistance of brazed diamond using Cu–Sn–Ti composite alloys reinforced with tungsten carbide

Abstract Diamond brazing is widely used in manufacturing wear–resistant tools. However, designing Cu–based filler metals with good welding characteristics and excellent mechanical properties remains a challenging task. In this work, diamond particles were connected to Q460 steel by using Cu–Sn–Ti composite fillers reinforced with different contents of micron–scale tungsten carbide (WC) particles. The microstructure of the brazing interface was analyzed via scanning electron microscopy and energy dispersive spectroscopy. The phase constitution of the brazed seam was characterized via X–ray diffraction. The effects of adding reinforcement on the mechanical properties of the vacuum brazed diamond samples were comprehensively analyzed and discussed. Results showed that the connection between diamond particles was effectively promoted by the addition of 15 wt% WC particles to the Cu–Sn–Ti fillers. The diamond and steel matrix were closely connected because of the formation of TiC and Cu Ti compounds. Samples with 15 wt% WC had a higher shearing strength and a lower abrasion loss than samples with different WC contents. Morphological examination of the wear surface showed that the interface reaction between WC and Cu–based filler alloys was tightly connected. Reinforcement with WC effectively improved the bonding strength and wear resistance of the samples. • The WC reinforced particles were added into Cu-Sn-Ti filler alloys to promote the strength and hardness. • The excessive wetting reaction was inhibited, and the exposure height of diamond particles was increased. • The effective grinding area was increased with the WC particles adding into fillers. • The shearing strength of the samples was significantly increased due to the WC reinforced Cu-Sn-Ti filler metals. • The coefficient of friction and grinding obstacle were lower, and the grinding performance was significantly improved.

High vacuum active brazing of cBN with improved composite filler: Microstructure, interfaces and performance evaluation

In this work, ceramic reinforcement of soft Ag–Cu–Ti filler alloy has been attempted to produce a superior filler alloy to braze cBN to steel in high vacuum conditions without compromising wettability and joint strength. 2 and 5 wt% of micro-alumina (μAl2O3) particles of average particle size (APS) 10 μm were added to Ti-activated (2 wt%) eutectic (72Ag28Cu) filler alloy as reinforcements for brazing Cubic Boron Nitride (cBN) particles (APS: 427 μm) to steel substrate. The alloy-matrix wetted μAl2O3 particles appreciably. Cu3Ti3O phase formed (confirmed through TEM/SAED-pattern analyses) and grew surrounding the μAl2O3 particles with a very thin interlayer of γ-TiO. Nano-hardness of Cu3Ti3O was measured to be 17.6±2.42 GPa. Cu3Ti3O together with μAl2O3 particles resulted in substantially enhanced (63–76%) abrasion-resistance characteristics of the primary alloy. 5 wt% addition of μAl2O3 to Ag–Cu–2Ti alloy displayed superior performance to 2 wt% addition. However, with higher proportion (5 wt%), wettability of the reinforced filler on cBN part got slightly impaired. Few micro-voids also surfaced on cBN-encapsulating bonding layer. Considering joint strength and wettability, 2 wt% of μAl2O3 is recommended to produce brazed cBN tools for high-impact load applications.

Brazing of porous Si3N4 ceramic to Invar alloy with a novel Cu–Ti filler alloy: Microstructure and mechanical properties

Porous Si3N4 (P–Si3N4) ceramic was successfully joined to Invar alloy using a Cu–Ti active brazing alloy for the first time. The interfacial reactions between the Cu–Ti filler and two dissimilar substrates were studied. The influence of brazing process on the microstructure evolution of the joint was revealed, along with the formation of an infiltration layer that permitted the bonding of P–Si3N4 substrate. Ti reacted with Si3N4 to form TiN and Ti5Si3 compounds, resulting in the decomposition of Si3N4. In addition, the reaction and diffusion dual-layer formed at the Cu–Ti/Invar interface, which was attributed to the interaction of alloy elements between the braze filler and the Invar alloy. Fe–Ti and Ni–Ti intermetallics together with Cu solid solution (s,s) constituted the microstructure of the brazing seam. In addition, the optimal shear strength of the brazed joint was 20 MPa and the fracture propagation occurred in the P–Si3N4 ceramic substrate adjacent to the infiltration layer during the shearing tests.

Brazing diamond grits onto AA7075 aluminium alloy substrate with Ag–Cu–Ti filler alloy by laser heating

The brazing of diamond is a promising way to fabricate grinding wheels for efficient machining and precision grinding. This work investigated the feasibility of bonding diamond grits onto Aluminium Alloy 7075 (AA7075) substrate with a Ag–Cu–Ti filler alloy via laser fusion brazing. The interfacial microstructures and the strength of the brazed diamond joints were studied. The cross-section of the brazed diamond joint consists of a molten filler alloy layer, a molten pool, a heat effect zone, a columnar crystal zone and an equiaxed crystal zone. Within the interface of the filler alloy/substrate metal, microstructures observed possibly were Ag(s.s), Al(s.s), TixAl, Al2Cu and Mg intermetallic compounds. A layer of TiC with a thickness of about 30–50 nm was found at the bonding interface of the diamond/filler alloy. The averaged peak shear force of the brazed joints was found to be approximately 39.8 N. The abrasion grinding test indicated that the diamond/AA7075 brazed joint was adequate for grinding. However, the pulled-off of grit was found to be the primary failure of this type of brazed joint. This work broadened the brazing diamond technique and the range of applications of brazed diamond wheels for efficient grinding.

Microstructures and bonding strength of synthetic diamond brazed by near-eutectic Ag–Cu–in–Ti filler alloy

Synthetic diamond is often bonded to metals or itself to fulfil the functional requirements for the applications in machine tools or the fabrication of thermal management materials. The knowledge on the relationship between interfacial microstructure and bonding strength of the synthetic diamond is therefore of significant scientific and technological implications. In this work, the epitaxial growth of titanium carbides formed on synthetic diamond grits brazed using a near-eutectic Ag–Cu–In–Ti active filler alloy was systematically investigated. An ultra-thin TiC layer was identified on the synthetic girts brazed at 680 °C and the epitaxial growth of Ti3InC carbides together with Ag3In and Cu2InTi intermetallics (IMCs) were subsequently examined at the brazing temperatures of up to 880 °C. The solidification microstructures of the Ag–Cu–In–Ti filler alloy in the brazed diamond joints were discussed based on composition analysis and phase diagram information. The growth morphologies of the interfacial products were exemplified by taking the bonding strength, fracture behaviours, and integrity of the brazed synthetic diamond into account. The results obtained would be of great value for developing diamond related devices and materials.

In Vitro Cytocompatibility Assessment of Ti-Modified, Silicon-oxycarbide-Based, Polymer-Derived, Ceramic-Implantable Electrodes under Pacing Conditions.

Polymer-derived ceramics (PDC) have recently gained increased interest in the field of bioceramics. Among PDC's, carbon-rich silicon oxycarbide ceramics (SiOC) possess good combined electrical and mechanical properties. Their durability in aggressive environments and proposed cytocompatibility makes them an attractive material for fabrication of bio-MEMS devices such as pacemaker electrodes. The aim of the present study is to demonstrate the remarkable mechanical and electrical properties, biological response of PDCs modified with titanium (Ti) and their potential for application as pacemaker electrodes. Therefore, a new type of SiOC modified with Ti fillers was synthesized via PDC route using a Pt-catalyzed hydrosilylation reaction. Preceramic green bodies were pyrolyzed at 1000 °C under an argon atmosphere to achieve amorphous ceramics. Electrical and mechanical characterization of SiCxO2(1-x)/TiOxCy ceramics revealed a maximum electrical conductivity of 10 S cm-1 and a flexural strength of maximal 1 GPa, which is acceptable for pacemaker applications. Ti incorporation is found to be beneficial for enhancing the electrical conductivity of SiOC ceramics and the conductivity values were increased with Ti doping and reached a maximum for the composition with 30 wt % Ti precursor. Cytocompatibility was demonstrated for the PDC SiOC ceramics as well as SiOC ceramics modified with Ti fillers. Cytocompatibility was also demonstrated for SiTiOC20 electrodes under pacing conditions by monitoring of cells in an in vitro 3D environment. Collectively, these data demonstrate the great potential of polymer-derived SiOC ceramics to be used as pacemaker electrodes.

Solution Strengthening the Ti-6Al-4V Joints were Brazed by Ti-15Cu-15Ni and Ag-26.7Cu-4.5Ti Filler Foils

Using the optimal solution and aging treatment for Ti-6Al-4V brazed by Ti-15Cu-15Ni and Ag-26.7Cu-4.5Ti fillers, the average shear strengths of the lap-joint interface are improved. And the average grain sizes and the average lengths of Widmanstätten structure are significantly smaller than that of post-brazed annealing. Both fillers specimens are examined to indicate the strengthening mechanism is to homogenize the microstructure of Ti-6Al-4V joints to simultaneously enhance the strength of joint braze and substrate.

Mechanical and microwave absorption properties of Ti-filled SiCf/SiC composites via precursor infiltration and pyrolysis

SiC fiber reinforced SiC ceramic matrix composite is a kind of promising high-temperature structure absorbing integrated material because of its good temperature resistance and high-temperature stability. However, the mechanical properties of the composites are poor and it is difficult to adjust the electromagnetic parameters. In this study, Ti powders were used as active fillers to improve the mechanical and microwave absorption properties of SiCf/SiC composites fabricated by polymer infiltration and pyrolysis (PIP) process. The compositions of SiC matrix derived from polycarbosilane (PCS) precursor modified by various content Ti powders were investigated by XRD and Raman spectroscopy. With the incorporation of Ti powders, free carbon decomposed from PCS was consumed due to the formation of TiC phase. The effect of Ti fillers on the mechanical and dielectric properties of SiC/SiC composites was also investigated. The flexural strength of SiCf/SiC composite was gradually improved with increasing Ti content owing to the improved density and TiC particle strengthening. Besides, consumption of free carbon in SiC matrix may impair the conductive network of free carbon, leading to decreased conductivity and the imaginary part of complex permittivity of the composite. Therefore, an optimum microwave absorption performance of SiCf/SiC composite with an RLm value of − 37 dB at 10.51 GHz and an effective absorption bandwidth of 3.28 GHz was obtained at the thickness of 2.5 mm and the Ti content of 5 wt%. The Ti-filled SiCf/SiC composite with superior microwave absorption property is a promising candidate in the high-temperature structure absorbing field.

Wetting behavior of AgCu–Ti filler metal on SiC ceramics surface pre-treated by ion bombardment

For the first time, the wetting behavior of SiC ceramics modified by ion bombardment was studied and the interfacial microstructure was characterized. An amorphous layer was formed on the SiC surface, which has significant influence on the wetting behavior and the interfacial microstructure of SiC/AgCu–Ti wetting system. The interfacial reactions were accelerated when filler melted on the bombarded SiC surface, and the spreading on the bombarded SiC ceramics was controlled by interfacial reactions firstly and then by diffusion. The spreading rates, kr, were denoted as kr,i = 42.28exp (-456.2/RT) for bombarded SiC, and kr,0 = 28.62exp (-329.9/RT) for the original one. Ion bombardment improved the bonding quality of ceramics/droplet interface effectively, a mixed reaction layer containing TiC and Ti5Si3 was formed and no reactant stratification was occurred at the interface of SiC/droplet.

Microstructure evolution and mechanical properties of ZrO2/ZrO2 joints brazed with Ni–Ti filler metal

Ni–Ti alloy was used as brazing filler to join ZrO2 ceramics and reliable joints were achieved. The effects of brazing temperature on the interfacial microstructure and mechanical properties of ZrO2/Ni–Ti/ZrO2 joints were investigated, the microstructure evolution during brazing and fracture mechanism of the joints were discussed. The results showed that a continuous reaction layer of TiO + Ni2Ti4O was formed adjacent to ZrO2 substrate, NiTi and Ni3Ti were formed at the center of brazing seam, in addition, ZrO2 substrate next to the brazing seam converted to non-stoichiometric ZrO2−x during brazing. With increasing brazing temperature, TiO decreased gradually and finally disappeared, whereas the thickness of Ni2Ti4O layer increased obviously and the reaction layer became discontinuous when the brazing temperature increased to 1350 °C and 1380 °C, besides, the morphology of Ni3Ti changed from bulk to strips and clumps. The maximum shear strength of the joint was 100.4 MPa when brazed at 1350 °C for 30 min.

Reactive wetting behavior and mechanism of AlN ceramic by CuNi-Xwt%Ti active filler metal

In order to propel the application of the developed CuNi-Xwt%Ti active filler metal in AlN brazing and get the universal reactive wetting mechanism between liquid metal and solid ceramic, the reactive wetting behavior and mechanism of AlN ceramic by CuNi-Xwt%Ti active filler metal were investigated. The results indicate that, with the increasing Ti content, surface tension for liquid CuNi-Xwt%Ti filler metal increases at low-temperature interval, but very similar at high-temperature interval, which influence the wetting behavior on AlN ceramic obviously. CuNi/AlN is the typical non-reactive wetting system, the wetting process including rapid wetting stage and stable stage. The wettability is depended on surface tension of the liquid CuNi filler metal completely. However, the wetting process of CuNi-8wt.%Ti/AlN and CuNi-16 wt%Ti/AlN reactive wetting system is composed by three stages, which are rapid wetting stage decided by surface tension, slow wetting stage caused by interfacial reaction and stable stage. For CuNi-8wt.%Ti/AlN and CuNi-16 wt%Ti/AlN reactive wetting system, although the surface tension of liquid filler metal is the only factor to influence the instant wetting angle θ0 at rapid wetting stage, the reduced free energy caused by interfacial reaction at slow wetting stage plays the decisive role in influencing the final wettability.