scispace - formally typeset
Search or ask a question

Showing papers on "Spray forming published in 2003"


Journal ArticleDOI
TL;DR: In this paper, an innovative spray-deposition technique has been applied to produce in situ TiC/Al and Al-20Si-5Fe-3Cu-1Mg composites, which can solve the problems of losses and agglomeration of the reinforcement particles when they are injected into the spray cone of molten droplets during spray forming process.

100 citations


Journal ArticleDOI
TL;DR: In this paper, the authors used a three-dimensional model of spreading and solidification to simulate interactions between droplets, and applied a fixed-grid Eulerian control volume method to solve the fluid dynamics and energy conservation equations.

83 citations


Journal ArticleDOI
TL;DR: In this article, the authors demonstrate the feasibility of rapid fabrication of near net shape nanostructured Al2O3 components of larger size by plasma spray forming technique using a proprietary cooling technique to retain a large fraction of nanosize powder particles in the spray deposit.
Abstract: The plasma spray technique has been used by several researchers to deposit nanostructured ceramic coatings, but there is no available literature discussing how to fabricate a bulk, freestanding nanostructured component by such a technique. In the current study, net shape nanostructured Al2O3 structures have been fabricated using the plasma spray technique. A detailed characterization of the spray-formed Al2O3 structure has been performed using x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and microhardness measurements. This study validates the feasibility of rapid fabrication of freestanding, near net shape nanostructured Al2O3 components of larger size by plasma spray forming technique. Plasma spray parameters were controlled with a proprietary cooling technique to retain a large fraction of nanosize Al2O3 powder particles in the spray deposit. Partially melted nanosize Al2O3 particles were trapped between the fully melted coarser, micrometer size Al2O3 grains. It was found that densification of the spray deposit has been dominated by both solidification and solid-state sintering. This study proves that a variety of nanostructured materials and their combinations can be fabricated to near net shapes by espousing a similar processing approach.

56 citations


Journal ArticleDOI
01 Aug 2003-Wear
TL;DR: In this article, the effect of spray forming on the wear properties of a 1.2C-3.4W-8.9Cr-4.3V-2.7Mo high speed steel is described.

47 citations


Journal ArticleDOI
TL;DR: The paper describes the design of a time-varying H/sub 2/ controller for the process and presents results from the implementation of the controller on the spray forming process.
Abstract: Spray forming is a novel method of rapidly manufacturing tools and dies for stamping and injection operations. The process sprays molten tool steel from a set of arc spray guns onto a ceramic former to build up a thick steel shell. The volumetric contraction that occurs as the steel cools is offset by a volumetric expansion taking place within the sprayed steel, which allows the dimensional accurate tools to be produced. To ensure that the required phase transformation takes place, the temperature of the steel is regulated during spraying. The sprayed metal acts both as a source of mass and a source of heat and by adjusting the rate at which metal is sprayed, the surface temperature profile over the surface of the steel shell can be controlled. The temperature profile is measured using a thermal imaging camera and regulated by adjusting the rate at which the guns spray the steel. Because the temperature is regulated by adjusting the feed rate to an actuator that is moving over the surface, this is an example of mobile control, which is a class of distributed parameter control. The paper describes the design of a time-varying H/sub 2/ controller for the process and presents results from the implementation of the controller on the spray forming process.

44 citations


Journal ArticleDOI
TL;DR: In this paper, the authors investigated the time dependent thermal conditions and solidification behavior in spray formed billets and compared with experimental results using a transient numerical simulation, and an investigation of the influence of different process parameters on the time-dependent temperature field and the solidification history within billets are shown.

32 citations


Journal ArticleDOI
TL;DR: In this paper, the influence of the G/M ratio in the spray forming process on the size of the primary Si phase in hypereutectic Al-Si alloy was investigated.

30 citations


Journal ArticleDOI
TL;DR: In this article, the processing, materials characterization, and applications of spray formed Cu-15Ni-8Sn, Cr12MoV steel, and GCr15 steel are reported.

26 citations


Journal ArticleDOI
TL;DR: In this article, an experimental investigation was performed to study the heat transfer process from the surface of a billet due to an oblique impinging circular gas jet, where the gas stream was generated by a circular array of 24 single jets within an atomizer nozzle.

23 citations


Journal ArticleDOI
TL;DR: In this paper, an experimental investigation into the use of the spray forming process to a high strength, high conductivity, copper alloy of composition Cu-1.33% Cr-0.78% Mg, with a refined microstructure increased solid solution of alloy elements, reduced oxidation and a high proportion of small precipitates.

18 citations


Journal ArticleDOI
TL;DR: In this paper, a novel technique in which TiC particulates are fabricated by an in situ reaction in molten aluminum is introduced for producing TiC/Al-20Si-5Fe composite.

Journal ArticleDOI
TL;DR: In this paper, the influence of the droplet dynamic and thermal behavior on the resultant microstructure has been studied, taking into account the higher Reynolds number owing to supersonic gas flow.
Abstract: Mathematical modeling of supersonic gas atomization for spray forming has been investigated. Influence of the droplet dynamic and thermal behaviour on the resultant microstructure has been studied. Analytical models have been constructed taking into account the higher Reynolds number owing to supersonic gas flow. The impact velocity profiles of the droplets lend credence to the evolution of equiaxed grain morphology through dendrite fragmentation. The thermal history profile along with the fraction solid plot could yield optimized standoff distance to obtain a mushy droplet. A comparison of secondary dendrite arm spacing obtained from the mathematical model showed good agreement with experimental observations.

Journal ArticleDOI
TL;DR: In this paper, the effects of spray distance on porosity, tensile strength and hardness of sprayed coatings were investigated and it was shown that with an increase in spray distance, shrinkage of the sprayed coating and the maximum temperature in the thermal analysis curve decrease.
Abstract: We investigate flame spraying of pure aluminum and pure zinc powders on various different substrates and study shrinkage properties and thermal analysis curves of sprayed coatings during the forming process. We also examined effects of the spray distance on the porosity, tensile strength and hardness of sprayed coatings, and obtained the following results. With an increase in spray distance, shrinkage of the sprayed coating and the maximum temperature in the thermal analysis curve decrease. When the cooling ability of the substrate is higher, the shrinkage ratio and the maximum temperature become decrease. The porosity and the hardness of a sprayed coating increase with an increase in spray distance. This occurs because with the increase in the spray distance, the temperature of the sprayed particles decreases, the amount of air taken in the spray increases and, as a result, the cooling rate of the coating increases. The tensile strength of a pure aluminum coating decreases with an increase in spray distance due to the introduction of pores. On the contrary, the tensile strength of a pure zinc coating increases with an increase in spray distance. This occurs because when the spray distance is short, coating temperature is high and, as a result, a large quantity of zinc oxide is formed.

Journal Article
TL;DR: Methods for manufacturing metal foams and other porous metallic structures are reviewed in this article, where liquid metal can he foamed directly by injecting gas or gas-releasing blowing agents, or by solid-gas eutectic solidification.
Abstract: Methods for manufacturing metal foams and other porous metallic structures are reviewed. Liquid metal can he foamed directly by injecting gas or gas-releasing blowing agents,or by solid-gas eutectic solidification. Investment casting, infiltration under pressure or vacuum, spray forming, and melting of powder compacts which contain a blowing agent could also be used for making metal foams. The sintering method,and metal powder slurry foaming can make metal foams even in the solid state. And electro-deposition and metal vapour deposition could also be applied to create highly porous metallic structures. Finally ,various applications of metal foams are discussed.

Patent
10 Jul 2003
TL;DR: In this paper, a spray-formed article is formed by spraying a plurality of metal streams upon a low-heat resistant model and thereby forming a spray formed article, each of the metal streams is composed of moltenized droplets.
Abstract: Method and arrangement for spray forming an article. The method includes spraying a plurality of metal streams upon a low-heat resistant model and thereby forming a spray formed article. Each of the plurality of metal streams is composed of moltenized droplets, and as between the plurality of metal streams, each is composed of different constituent elements. In the spray form process, conditions of the metal streams are controlled, particularly around the time that the droplets land, to prevent adverse affects such as melting or burning the master model. The spray conditions are controlled in such a manner that the individual metal droplets forming the metal streams remain substantially segregate. The segregated state is maintained through out solidification so that the resulting spray formed article is composed at least partially of psuedo-alloy.

Patent
10 Feb 2003
TL;DR: In this article, a method for spray forming metal deposits is described, which is comprised of providing a ceramic substrate having a spraying pattern for receiving sprayed metal particles, spraying metal particles onto the spraying pattern to form a metal deposit on the pattern for at least a first spray period, controlling the spraying step during the first spraying period so that the temperature of the deposited metal particles increases at an average rate of less than or equal to about 15° per minute.
Abstract: One method of the present invention relates to a method for spray forming metal deposits. The method is comprised of providing a ceramic substrate having a spraying pattern for receiving sprayed metal particles, spraying metal particles onto the spraying pattern to form a metal deposit on the spraying pattern for at least a first spray period, controlling the spraying step during the first spray period so that the temperature of the deposited metal particles increases at an average rate of less than or equal to about 15° per minute. The first spray period can be defined as lasting until the temperature of the deposited metal particles is at or about a steady state temperature. The steady state temperature is preferably in the range of about 330° C. to about 370° C.

Patent
16 Oct 2003
TL;DR: In this article, a series of tool steels for spray forming die inserts comprising iron, carbon, silicon, manganese, chrome, molybdenum and vanadium were described.
Abstract: The invention relates to a series of tool steels for spray forming die inserts comprising iron, carbon, silicon, manganese, chrome, molybdenum and vanadium. According to the invention the vanadium content is over 1,4 w-%. Further more the invention relates to a method of rapid tooling by spray forming in which a melted tool steel is as above, and it is atomized and sprayed onto a ceramic mould under the atomizer. Further more the ceramic mould is rotated under the atomizer and the rotating axis of the mould is tilted from the spraying direction to a deposition angle.

Patent
04 Feb 2003
TL;DR: In this article, a method of spray forming a boron steel metal article is described, in which a spray forming pattern is provided, and metallic particles are sprayed from a carbon steel feedstock having a 025-225 weight percent, based on the total weight of the feedstock.
Abstract: The present invention relates to a method of spray forming a boron steel metal article, and to the formed article In at least one embodiment, the method comprises (a) providing a spray forming pattern, (b) spraying metallic particles onto the spray forming pattern, and (c) allowing the sprayed metallic particles to cool to form a metal article In at least one embodiment, the metallic particles are sprayed from a carbon steel feedstock having a boron content of 025-225 weight percent, based on the total weight of the feedstock

Journal ArticleDOI
TL;DR: In this paper, a 2.9%C-22%Cr white cast iron was processed by spray forming aiming to investigate the potential of achieving novel microstructure by the high cooling rate involved in this process.
Abstract: In the present work a 2.9%C-22%Cr white cast iron was processed by spray forming aiming to investigate the potential of achieving novel microstructure by the high cooling rate involved in this process. Two gas flow rate to metal flow rate ratios (0.12 and 0.23) were used. The microstructural characterization was performed by using X-ray diffractometry, optical and scanning electron microscopy. The conventional microstructure of this alloy shows M 7 C 3 carbides (about 300 μm in length) embedded in a matrix of austenite and martensite dendrites; on the other hand the spray formed deposit showed a microstructure formed by fine M 7 C 3 carbides (less than 10 μm in length) in a martensitic matrix. The overspray powders showed a microstructure composed mainly by carbides and austenite; the relatively rapid solidification of the droplets enhanced the chromium and carbon solubility in austenite changing the Ms temperature.

Journal ArticleDOI
TL;DR: In this article, the effects of the materials, deformation temperatures and initial strain rates on the softening phenomenon of spray forming Si particles were investigated with compressive stress-strain curves.
Abstract: Si particles were in-situ generated during spray forming to form Al/SiP MMCs with 28% and 38% of SiP and AC9A MMC containing 29 v/o of SiP. The large difference between the sizes and distributions of Sip generated by spray forming and by casting was investigated. The workability of the MMCs was studied by compressive testing. The effects of deformation temperatures and initial strain rates on the workability of the MMCs were investigated with compressive stress-strain curves. Softening phenomenon following peak stresses due to dynamic recrystallization was shown in most cases, while continuously hardening without softening was also found. The effects of the materials, deformation temperatures and initial strain rates on the softening phenomenon were studied. The strain rate sensitivity is discussed along with the effects of deformation temperatures and initial strain rates.

Journal ArticleDOI
TL;DR: In this paper, the disintegration of the molten metal occurring during spray forming is an essential step in a semi-finished metal manufacturing process, which leads to fine equi-axed grain structures and therewith to characteristic and desired material properties.
Abstract: Spray forming is a new production process for manufacturing semi-finished metal products. The procedure combines the liquid metal atomization with the compaction event of the generated metal droplets on a substrate. During spray forming, the heat emission of the molten metal particles is one of the most important transfer operations defining the thermal conditions in the spray and deposit. Definite thermal conditions throughout the manufacturing process lead to fine equi-axed grain structures and therewith to characteristic and desired material properties. Thus, in particular, the disintegration of the molten metal occurring during spray forming is an essential step.

01 Jan 2003
TL;DR: In this paper, the authors deal with the heat evolution duringsolidification and its relation to the formation of porosity, and improve the current understanding of theformation of the porosity in cast mate.
Abstract: This thesis deals with the heat evolution duringsolidification and its relation to the formation of porosity.It intends to improve the current understanding of theformation of porosity in cast mate ...

Patent
03 Jul 2003
TL;DR: In this paper, the formation of a spray-formed product by spraying a plurality of metal flows on a low-heat-resistant model is described, where the state of the metal flow is controlled especially at about a point of time of landing of the liquid drops, thus preventing such an undesirable influence as to fuse or burn a master model.
Abstract: PROBLEM TO BE SOLVED: To enable a direct spraying of a metal on a model made of a low- heat-resistant material. SOLUTION: This method includes the formation of a spray formed product by spraying a plurality of metal flows on a low-heat-resistant model. Each of a plurality of metal flows consists of fused metal drops, and the constituting elements of the plurality of metal flows are different from each other. In the process of spray forming, the state of the metal flow is controlled especially at about a point of time of landing of the liquid drops, thus preventing such an undesirable influence as to fuse or burn a master model. The spray conditions are controlled so that each of fused metal drops forming the metal flow is substantially kept separated; this separated state is maintained during the solidification process so as to give a final spray formed product at least partially consisting of a pseudoalloy. COPYRIGHT: (C)2003,JPO

Patent
12 Mar 2003
TL;DR: In this paper, a method of manufacturing a cylinder block for an engine is provided, which improves contact among materials, settle a contact problem made by difference of thermal expansion coefficient, and prevent generation of defect in casting the cylinder block.
Abstract: PURPOSE: A method of manufacturing a cylinder block for an engine is provided to improve contact among materials, settle a contact problem made by difference of thermal expansion coefficient, and prevent generation of defect in casting the cylinder block. CONSTITUTION: A method of manufacturing a cylinder block for an engine comprises steps of manufacturing an aluminium alloy cylinder liner, by a spray forming method(S1); installing the aluminum alloy cylinder liner in a metal mold for casting a cylinder block(S2); and casting the cylinder block by injecting aluminum alloy liquid metal under high pressure into the metal mold(S3). Since the cylinder liner of the same material, manufactured by the spray forming method is installed, contact among materials is improved.

Journal ArticleDOI
TL;DR: In this article, the influence of process parameters on the microstructural behavior of Fe-6.5%Si deposits was studied, and the studied parameters were: gas/metal mass flow rate (GMR), the atomization nozzle-to-substrate distance and the substrate material.
Abstract: The microstructural evolution of spray formed materials depends on the thermal and dynamic behavior of the atomized droplets during their trajectory in direction of the substrate, which are governed by process parameters. In the present work, the influence of process parameters on the microstructural behavior of Fe-6.5%Si deposits was studied. The studied parameters were: gas/metal mass flow rate (GMR), the atomization nozzle-to-substrate distance and the substrate material. It was noticed that with the increase of nozzle-to-substrate distance or of the GMR, the porosity volumetric percentage increased, while grain size was reduced. Use of ceramic substrate resulted in porosity decrease and grain size increase when compared to results obtained with the use of water-cooled metallic substrate.

Patent
15 Jul 2003
TL;DR: In this article, a spray-forming GRC (glass fiber reinforced cement) is used to provide a glass roving for a spray forming GRC which has high initial mechanical strength and can suppress the degradation in the mechanical strength of the GRC for long time.
Abstract: PROBLEM TO BE SOLVED: To provide a glass roving for a spray forming GRC (Glass fiber Reinforced Cement) which has high initial mechanical strength of the GRC and can suppress the degradation in the mechanical strength of the GRC for long time. SOLUTION: The glass roving is composed of glass fibers which contain ≥14 mass% ZrO 2 and are formed by treating their surfaces by a sizing agent. The sizing agent contains an ethylene vinyl acetate copolymer having ≥5 mass% content of ethylene at ≥55 mass% in the solid content of the sizing agent. COPYRIGHT: (C)2003,JPO

Journal ArticleDOI
TL;DR: In this article, the microstructures and mechanical properties of three cylinder liners: grey cast iron; and two aluminium silicon alloys were evaluated, and their surface roughness and topology also have been investigated.
Abstract: The automotive industry is seriously concerned with emission level control, vehicle weight reduction and recycling. These are the purposes of introducing the all aluminium cylinder blocks for the combustion engine. The spray forming process led to the fabrication of cylinder liners made of high aluminium silicon alloys. The aim of the present work was to evaluate and compare the microstructures and mechanical properties of three cylinder liners: grey cast iron; and two aluminium silicon alloys. Their surface roughness and topology also have been investigated.


Journal ArticleDOI
TL;DR: In this article, the Fe 83 Nb 4 Zr 1 Ti 1 B 9 Cu 2 (%at) alloy was processed by spray forming with the aim of investigate the formation of novel microstructures by the high cooling rate involved in this process.
Abstract: In this study the Fe 83 Nb 4 Zr 1 Ti 1 B 9 Cu 2 (%at) alloy was processed by spray forming with the aim of investigate the formation of novel microstructures by the high cooling rate involved in this process. The ratio between the gas mass flow rate (kg/min) and the metal mass flow rate (kg/min) used was 0.25, and nitrogen was used as the atomization gas. The resulting billet, weighting about 0.8 kg, as well as the overspray powders, with a median particle diameter about 150μm, were characterized by using X-ray difflatometry, differential scanning calorimetry and scanning and transmission electron microscopy. The microstructure observed in both overspray powder and deposit was fully crystalline formed by α-Fe, fcc-Cu and the intermetallic Fe 2 Zr phases. SEM together with the EDS analysis of these phases is presented. The Fe 83 Nb 4 Zr 1 Ti 1 B 9 Cu 2 (%at) alloy presented a very fine microstructure of the α-Fe grains which decreases as the granulometric size ranges of the overspray powder diminishes due to the increasing in the cooling rate. The deposit showed irregular porosity due to the high fraction of solid particles that hit the substrate during deposition stage.

Patent
07 May 2003
TL;DR: In this paper, a flat fan-shaped spray pattern is used to form articles from a polyurethane composition, where repeated passes of the nozzle that partially overlap apply a deposit in a series of parallel paths.
Abstract: A method of spray forming articles with a nozzle that sprays in a flat fan-shaped spray pattern. The process may be used to form articles from a polyurethane composition. Repeated passes of the nozzle that partially overlap apply a deposit in a series of parallel paths. A primary flat fan-shaped spray is flanked by a pair of secondary sprays that are outboard of the primary spray. The secondary sprays facilitate feathering the edges of adjacent deposits and provide a spray application having a consistent thickness.