Liquid Filler Research Articles

Visual observations of liquid filler metal flow within braze gap

An in situ visualisation technique has been developed to observe liquid metal flow through a controlled gap. The technique can image and measure brazing filler metal flow velocities, positions, contact angles, and fillet shape. The system captures the two-dimensional fluid flow kinetics common in most capillary driven processes. It consists of a fully integrated, digital, closed loop heating station and a high speed digital camera. The apparatus provides an accessible approach for gathering dynamic braze wetting and flow data that are normally difficult to obtain in a furnace environment. Braze flow displacement curves are generated from the processed camera images. The flow data are being used to calibrate and validate a braze flow model that will predict the effects of dissolution, diffusion, compositional changes, and solidification on capillary fill and fillet geometry.

A dissolution model of base metal in liquid brazing filler metal during high temperature brazing

Controlling the dissolution of the base metal in the liquid filler metal is very significant for both brazing and soldering processes, in particular for high temperature brazing. A model for quantitatively evaluating the dissolution thickness of base metal in liquid brazing filler metal is established, that produces consistent predictions with experiment.

Surface wetting and interfacial behaviour in arc brazing of titanium alloy

The spreading behaviour of Cu, CuSi, CuMnNi, and TiCuNi filler metals with Ti6Al4V titanium alloy base metal has been studied under gas tungsten arc welding heating. Test results showed that the wet angle of CuMnNi filler metal was the smallest (15 ° ) and that of Cu was the largest (30 ° ). With spreading, the liquid filler metal solidified and crystallised simultaneously, and formed a spherical crown brazing seam. The wettability and spreadability of the liquid filler metal were related to oxide scale actions with arc heating. These actions included the 'cleaning action of the cathode' and lashing activation action of electrifying ions and electrons. Furthermore, the very high temperature of the activation spot zone partly melted the base metal surface and near surface metal, and a thin liquid film was accordingly formed that created a strong heating activation. It was also discovered that there was a column solid - liquid incongruent compound η (MeTi2) at the interface of filler metal and base metal (Me + Cu, Cu + Ni, Cu + Mn). This compound grew to form an interface with the centre of the brazing seam and was embedded in it. The particular crystallising and growing mode in the arc heating helped grow the column solid - liquid incongruent compound η (MeTi2).

Phase morphology and molecular dynamics of a polyurethane ionomer reinforced with a liquid crystalline filler

Solution-blended binary composites of ionic segmented polyurethane (SPU-I) and liquid crystalline oligomer (LCO) were characterized by wide-angle (WAXS) and small-angle (SAXS) X-ray scattering, differential scanning calorimetry (DSC), thermally stimulated depolarization currents (TSDC) and dielectric relaxation spectroscopy (DRS). Both components mutually influenced their states of aggregation in blends (most significantly, promoting smearing-out of interfaces between stiff and soft chain fragments of SPU-I into broad interfacial regions of intermediate composition). Apparently, the blend with w=0.10 happened to be most favorable for crystallization of the LCO, while the degree of microphase separation for SPU-I became lower and the distribution of stiff domains by sizes became broader, the higher the LCO content. The overall molecular mobility of SPU-I in blends was significantly reduced. This reduction included the intensity of the secondary and the primary relaxations, and of the interfacial Maxwell–Wagner–Sillars (MWS) relaxation, whereas the transition temperatures remained essentially composition-invariant. The Arrhenius-like behavior for the dc conductivity concomitant to the non-Arrhenius (i.e., Vogel–Tammann–Fulcher) frequency dependence for the α relaxation in blends suggested a decoupling of conductivity from the motion of the SPU-I soft chain segments.

Braze Pressure Welding (BPW)-A New Method for High Quality Pressure Welding

Braze Pressure Welding (BPW) with high frequency induction heating has been invented as the new joining method for welding general steel pipes for on-site piping without the danger of fire and the dispersion in the joint properties due to welder's skill. In the BPW, a brazing filler is interlaid between the mating surfaces to be joined. The filler melts by heating up to joining temperature, then the welding pressure discharges it from the joining interface. At the same time, the base metals are pressure-welded to each other, and that the discharged liquid filler forms fillets around the joining area. The fillets have the effects both on relaxing the stress concentration at the joint and on increasing the joining area, which contributes to the strengthening of joint. Experimentally it was revealed that the BPW joints had superior properties to brazed or pressure-welded joints by microscopy, EDS analysis, and tensile test of joints. The effect of the fillet on relaxing the stress concentration at the joint area was also confirmed by finite element analysis.

Fluid mechanics of laminated sheet manufacture

The fluid mechanics of laminated sheet manufacture was studied by pouring a liquid filler from a point source onto an inclined moving sheet and then passing it under a narrow gap below a pinch bar that spreads the liquid under the influence of gravity. The liquid filler must pass under the pinch bar before it starts to solidify. The spreading of a viscous liquid as it undergoes this process was studied theoretically and experimentally. Steady similarity solutions were obtained based on a vertically averaged formulation of the mass and momentum equations for viscous flows. Experimental measurements of the spread of the fluid and the time taken for fluid to travel from the source to the pinch bar agreed well with theoretical predictions. The new models are applied to the operation of the manufacturing process and the implications are discussed.

Microstructure–fracture toughness relationship of vanadium alloy/stainless steel brazed joints

In this work, brazing V–5Ti–5Cr to 304 stainless steel (SS 304) using Au–18Ni alloy as filler material was conducted under high vacuum condition. Sessile drop technique was used to determine the wettability of filler alloy to the stainless steel and the vanadium alloy substrates upon which the relationship between the contact angles with time was obtained. Tensile tests were performed on unnotched and notched specimens to demonstrate the overloading behavior and the fracture toughness of the base materials and the brazed joint. Fracture surface was examined for both the V–5Ti–5Cr and the joint to identify the failure mechanisms under static loadings. It was found that the Au–18Ni filler material exhibited good wettability with the SS 304 and V–5Ti–5Cr. The ultimate tensile strength of the brazed joint reached 245 MPa. The strain to failure was about 1.3%. Young's modulus was about 351 GPa. The fracture toughness ( K Ic) of this joint was 19.1 MPa √ m . The fracture surface of the joint showed well brazed area with good wettability and proper amount of residual filler material which came from the solidification of residual liquid filler alloy of Au–Ni. The failure of the joint occurred along the interface of the vanadium/filler under static load.

Nonlinear problems of the dynamics of elastic shells partialiy filled with a liquid

Theoretical and experimental investigations of the nonlinear vibrations and dynamic stability of thin shells partially filled with a liquid are reviewed. The paper deals with the basic laws governing the dynamic high-deflection deformation of carrying shell structures and the considerable vibrations of the free liquid surface due to the natural, forced, and parametrically excited vibrations of the combined system and also due to impulse loads acting on the carrying object. The nonlinear dynamic interaction of shells with a liquid filler is analyzed with allowance for the wave motions of the free liquid surface.

チタンとニッケルのろう付過程における反応機構

A commercially pure titanium has been liquid phase diffusion bonded to pure nickel by using amorphous alloy filler metal.The dissolution phenomenon of the base metals into the liquid filler metal and the isothermal solidification process during bonding was investigated. Main experimental results obtained in this reserch are as follows;(1) The dissolution phenomenon of the base metals into the liquid filler metal was completed rapidly, its time was about 60 sec at 1125 and 1150 K, and about 120 sec at 1200 K.(2) The dissolution of titanium base metal shown a value three times as much the dissolution of nickel base metal into the liquid filler metal. The maximum dissolution width of the base metals were related to the boning temperature by the following equations.WDTi=(1.78×10-6×T)-(1.99×10-3), WDNi=(4.85×10-7×T)-(5.37×10-4)(3) The relation between dissolution parameter P of the base metals and bonding time dose not shown by the straight line relation, the dissolution process was divided into three stage according to the dissolution rate constant K. therefor, the dissolution phenomenon does not conformed to the Nernst-Brunner's theory.(4) The concentration of each elements were distributed itself uninformly throughout the bonded interlayer after the dissolution phenomenon of the base metals was completed.(5) The maximum width of the bonded interlayer was related to the boning temperature by the following equation.WBImax=(2.32×10-6×T)-(2.55×10-3)(6) The Ti-Cu and Ti-Ni system intermetallic compound layers formed on the interface of titanium base metal to the bonded interlayer. The Ti-Ni system intermetallic compound layer formed on the interface of nickel base metal to the bonded interlaver.

Acoustic methods for classification of fluids in sealed containers for identification of hazardous chemicals

There are many situations where it is necessary to be able to determine information about the liquid contents inside sealed or otherwise inaccessible containers. Typically for classification of a liquid filler, one needs to determine some simple properties of the liquid contents, such as the sound speed, density, and attenuation of the liquid. This information is often sufficient to identify and characterize various subclasses of chemicals. In cases where the containers are to contain hazardous chemicals (e.g., chemical warfare agents, highly toxic chemicals, highly flammable liquids, etc.) it may be unsafe for operators to make measurements using traditional techniques which require direct contact with the contents. This talk will address several techniques which address fluid classification for situations where direct contact with the fluid is not feasible. It will concentrate on methods which couple acoustic energy into the interior container cavity (by means of direct contact or stand-off methods) to extract frequency dependent acoustic information to serve as classification clues to identify the filler.

Mechanical properties of polymers containing fillers

The addition of fillers can significantly change the mechanical characteristics of a material. In this paper, a general, mechanistic model is established to determine the moduli, relaxation moduli, break strengths, and break strains for polymer films containing liquid and solid micro fillers. Based on rigorous continuum mechanics principles, this model considers the filler/filler interactions, incorporates the nonlinear synergistic effects of fillers, and provides accurate predictions in comparison with experimental data. The analytical model developed provides information that is not available or extremely difficult to obtain experimentally. The model can be applied to determine the filler/matrix adhesion and filler modulus using measured modulus of a filled polymer film (a filled polymer is a polymer containing fillers). It is found that the compression moduli of polymer films containing liquid fillers differ significantly from the tension moduli, especially when the volume fraction of the filler is high. The difference in compression and tension Young's moduli normalized by the tension Young's modulus is as high as 35%. The relative error in maximum pressure calculation during Hertzian contact caused by using the tension moduli is as high as 48%. The relaxation modulus of a filled polymer film is determined through inverse Laplace transforms of its composite modulus in the s-space. For a filled polymer film containing liquid phase fillers, a closed form solution for its relaxation modulus has been obtained. It is found that the composite relaxation modulus of the filled polymer is proportional to the relaxation modulus of the matrix polymer multiplied by a factor related to the volume fraction of the liquid filler. The break strength of the filled polymer is found to be proportional to the break strength of the polymer matrix material multiplied by a power function of the modulus ratio of filled polymer to polymer matrix, R. The break strain of the filled polymer is proportional to the break strain of the polymer matrix multiplied by a power function of 1/R. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 155–172, 1999

Calculation of the temperature field of heated transport cylinders with a liquid filler

The concentrated element method allows efficiently solving problems of calculating the temperature field of multiphase objects. Numerical modeling of thermal processes in an induction-heated drum with a liquid filler allowed selecting the rational drum design that ensured a high degree of uniformity of the temperature field around its working zone. The method can be used in designing not only cylinders but also other heated equipment.

Relationship between material parameters and target strength of fluid-filled spherical shells in water: calculations and observations

Thin fluid-filled spherical shells have been used as passive sonar targets for many years. They possess a large target strength which is highly dependent on the sound-speed mismatch between the fluid contained within the shell and the exterior fluid surrounding the shell. In the past, to obtain the appropriate mismatch, the interior fluid mixture contained chlorofluorocarbons (CFCs). Due to a recent production ban on CFCs, it is necessary to choose alternative fluids. The present research analyzes the backscattering target strength of a fluid-filled spherical shell as a function of several material parameters as a guide to choosing alternative fluids and shell materials. Calculations over a broad range of material values display the target strength dependence on the interior fluid parameters as well as the parameters defining the metallic shell. The range of material values presented here is far larger than any previous study addressing the focusing effects of fluid-filled spherical shells. The results should aid in determining liquid fillers and shell materials which yield the maximum possible backscattered returns. Also, several experiments were conducted with stainless steel shells containing a hydrochlorofluorocarbon (HCFC), dichlorofluoroethane. The results are compared with results found from calculations as well as from other experiments involving shells containing a previously used CFC mixture.

Composite foundation elements and sleeve-torus technologies for their construction

Principles for the design of composite foundation elements and sleeve-torus technologies for their construction, which include the use of casings formed from flexible materials (engineering fabrics, films, meshes) and thin-fiber reinforcement (fibers, filaments, bundles), the formation of workings by compaction of bed soils during the embedment of casings by reversing them and inflating them under pressure with gas, liquid, and mixed filler are presented. The ranges of application of the structures and procedures are detailed in the examples of a hollow cast-in-place pile, an anti-seepage curtain, an insulating-mat roller-compacter, and a hole expander, as well as in the trenchless laying of an embedded arterial pipeline.

Effects of fillers on wire sweep in semiconductor chip encapsulation

Epoxy molding-compounds which are used in semiconductor chip encapsulation by transfer molding are filled with high concentrations of silica particles whose dimensions are comparable to the diameter of the bonding wire. This study is aimed at investigating the effects of solid fillers on wire deformation during encapsulation. Experiments were performed to measure wire deformation due to the flow of a mixture of liquid and solid fillers. Wire deformation was determined by measuring the change in electrical resistance of the wire when it deformed and relating the change in electrical resistance to wire deformation. Next, the wire deformation was calculated based on the viscous drag force of the fluid on the wire. A theoretical estimate of the magnitude of the wire deformation due to direct particle collision was made which indicated that this is negligible compared with that due to the viscous drag force. The experimental wire deformation values were in good agreement with wire deformation values calculated based on the viscous drag force of the fluid.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Advances in brazing of ceramics

The main parameters in direct brazing of ceramics to ceramics and to metals are reviewed, with primary emphasis on those influencing wetting of solid ceramics by liquid filler metals. In general, wetting of ceramics by conventional brazing alloys has been regarded as difficult. As a consequence, premetallization of the faying surfaces is frequently used to facilitate the brazing of ceramics. However, it is evident from the literature that recent developments in filler metals, based on active metal (e.g. Ti) additions (the amount depending on alloy composition and type of ceramic), have provided a basis for a substantial reduction of the contact angle. This favourable effect is caused by their reactivity, resulting in the formation of oxides when joining oxide ceramics (e.g. Al2O3), and nitrides or carbides and suicides in the case of nonoxide ceramics (e.g. Si3N4 or SiC). In addition to insufficient wetting, the mismatch in thermal expansion between the joint members may give rise to a low strength level due to the formation of high residual stresses on cooling. These stresses may limit the maximum allowable flaw size in ceramics to a few micrometres, i.e. of a similar size to that of pores.

Quantitative measurement of attenuation and other parameters on biopsy samples of fresh tissue using acoustical microscopy

The Sommerfeld-Watson transformation, the reflection method and the theory of graphs are used to investigate the components of the echo-signal from a hollow elastic sphere with a concentric liquid filler, formed by reflection and rereflection at the media interfaces.

The interaction of reaction-bonded silicon carbide and inconel 600 with a nickel-based brazing alloy

The objective of the present research was to join reaction-bonded silicon carbide (RBSC) to INCONEL 600 (a nickel-based superalloy) for use in advanced heat engine applications using either direct brazing or composite interlayer joining. Direct brazing experiments employed American Welding Society (AWS) BNi-5, a commercial nickel-based brazing alloy, as a filler material; composite interlayers consisted of intimate mixtures of α-SiC and BNi-5 powders. Both methods resulted in the liquid filler metal forming a Ni-Si liquid with the free Si in the RBSC, which, in turn, reacted vigorously with the SiC component of the RBSC to form low melting point constituents in both starting materials and Cr carbides at the metal-ceramic interface. Using solution thermodynamics, it was shown that a Ni-Si liquid of greater than 60 at. pct Ni will decompose a-SiC at the experimental brazing temperature of 1200 ‡C; these calculations are consistent with the experimentally observed composition profiles and reaction morphology within the ceramic. It was concluded that the joining of RBSC to INCONEL 600 using a nickel-based brazing alloy is not feasible due to the inevitability of the filler metal reacting with the ceramic, degrading the high-temperature properties of the base materials.

Weld formation in welding with liquid filler metal

Weld formation in welding with liquid filler metal

Calculation of heat distribution in welding aluminium alloys with liquid filler metal with simultaneous milling of the edges

Calculation of heat distribution in welding aluminium alloys with liquid filler metal with simultaneous milling of the edges