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Showing papers on "Spray forming published in 2001"


Reference BookDOI
16 Oct 2001
TL;DR: In this paper, the basic fundamentals of casting process modelling stress analysis defect formation and prediction microstructure evolution thermophysical properties quick analysis electronic data interchange sand casting lost foam casting investment casting permanent mould casting die casting semi-solid metalworking continuous casting direct chill casting vacuum arc remelting and electroslag remelts plasma arc melting and electron beam melting spray forming.
Abstract: Fundamentals of casting process modelling stress analysis defect formation and prediction microstructure evolution thermophysical properties quick analysis electronic data interchange sand casting lost foam casting investment casting permanent mould casting die casting semi-solid metalworking continuous casting direct chill casting vacuum arc remelting and electroslag remelting plasma arc melting and electron beam melting spray forming.

118 citations


Journal ArticleDOI
TL;DR: The silicon content was increased up to 6.5% to reduce the power loss of the silicon steels as mentioned in this paper, but the difference in casting method did not result in any difference in suppressing the B2 ordering.
Abstract: The silicon content was increased up to 6.5% (by weight, unless specified otherwise) to reduce the power loss of the silicon steels. These steels were prepared by the conventional casting method or by spray forming and were investigated with the aid of light optical microscopy (LOM) and transmission electron microscopy (TEM). The difference in the casting method did not result in any difference in suppressing the B2 ordering. The D03 phase was observed only in the as-cast 6.5%Si steel. It was almost impossible to suppress the B2 ordered phase keeping the silicon level as high as 6.5% even after the heat treatment at 1000°C for 24 h or after hot rolling. It was necessary to change the Si level and control the cooling rate to suppress the ordering reaction, especially, in cooling after heat treatment. The silicon level of 5.87% was observed to be a critical value in suppressing the B2 ordering reaction. © 2001 Elsevier Science B.V. All rights reserved.

90 citations


Journal ArticleDOI
TL;DR: In this paper, the microstructural characteristics and mechanical properties of spray-deposited and hot extruded Al-6.5Si and Al-18Si alloys have been investigated.
Abstract: The microstructural characteristics and mechanical properties of Al–6.5Si and Al–18Si alloys have been investigated. The alloys were spray-deposited and hot extruded at 480°C with an area reduction ratio of 6:1. The microstructure of the spray-deposit of Al–6.5Si alloy showed spherical morphology of the primary α-phase with a globular shape of the eutectic Si phase in the inter-particle boundaries. On the other hand, a fine particulate morphology of primary Si phase uniformly dispersed in the matrix of the α-phase was observed in spray-deposit of Al–18Si alloy. Microstructural refinement was further increased in the hot extruded alloys. The room temperature tensile tests of spray formed and extruded alloys showed considerable increase in their strength and ductility over that of the as cast alloys. The improvement in mechanical properties of spray formed alloys is discussed in light of the microstructural modifications induced during spray deposition process.

77 citations


Patent
18 Jun 2001
TL;DR: In this article, the authors describe methods and apparatus for atomization and heat transfer with non-equilibrium plasmas, particularly for use in gas turbine engines, produced by the methods of the invention.
Abstract: The present invention is directed to methods and apparatus that use electrostatic and/or electromagnetic fields to enhance the process of spray forming preforms or powders. The present invention also describes methods and apparatus for atomization and heat transfer with non-equilibrium plasmas. The present invention is also directed to articles, particularly for use in gas turbine engines, produced by the methods of the invention.

50 citations


Journal ArticleDOI
TL;DR: In this article, the cold workability of high-Si steel was investigated by varying heat treatment conditions, such as ingot casting, spray forming, and B2 ordered phase, Si content, working temperature and Si-oxide.

45 citations


Journal ArticleDOI
TL;DR: In this paper, two ratios of volumetric gas flow rate to mass of metal flow rate (G/M) were used for the Al 85 Y 8 Ni 5 Co 2 alloy.

36 citations


Patent
05 Jun 2001
TL;DR: A spray forming system for the manufacturing of near-net-shape molds, dies, and related toolings is described in this paper, where liquid material such as molten metal, metallic alloys, or polymers are atomized into fine droplets by a high temperature, high velocity gas and deposited onto a pattern.
Abstract: A system for the spray forming manufacturing of near-net-shape molds, dies and related toolings, wherein liquid material such as molten metal, metallic alloys, or polymers are atomized into fine droplets by a high temperature, high velocity gas and deposited onto a pattern (34). Quenching of the in-flight atomized droplets by a quench gas in a chamber (51) provides a heat sink, thereby allowing undercooled and partially solidified droplets to be formed in-flight. Composites can be formed by combining the atomized droplets with solid particles such as powders, whiskers or fibers.

30 citations


Journal ArticleDOI
TL;DR: In this article, the Al84Y3Ni8Co4Zr1 alloy has been processed by spray forming to investigate the potential of achieving substantial fractions of the amorphous phase in the billet.
Abstract: In this investigation the Al84Y3Ni8Co4Zr1 alloy has been processed by spray forming to investigate the potential of achieving substantial fractions of the amorphous phase in the billet. The alloy was prepared by spray metal forming using the ratio of volumetric gas flow rate to mass of metal flow rate of 8.7 m 3 / kg . The resulting billet, weighting 2.1 kg, as well as the powders produced by the particles that had not hit the growing billet (overspray), were characterized by using X-ray diffractometry (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The powders had particles with spherical morphology in the size range of few microns to 100 μm with the median particle diameters about 20±1 μ m. The resulting billet contained only crystalline phases nevertheless the powder was composed of about 40% volume fraction of amorphous phase. This result indicates that the heating of the billet, by the heat release during solidification of the liquid and semi-solid particles was at temperature and for time enough for crystallization.

29 citations



Journal ArticleDOI
TL;DR: In this paper, the fundamental differences between spray forming and other semisolid processes are discussed, and a simple experiment was designed to give supporting evidence to this view, showing a unique thermal and solute profile on the deposit surface, resulting from the mixing of rapidly solidified metal formed during atomization and the solute-poor liquid formed by addition of the liquid of alloy composition, which contributes mainly to the microstructural evolution during spray forming.
Abstract: The distinguished microstructural features of spray formed products are the refined equiaxed grain structure and lower segregation level. Attempts have been made in the past to propose mechanisms to explain the formation of equiaxed grain structure. Recently there has been a tendency in correlating spray forming with other semisolid processes such as liquid phase sintering (LPS) and rheocasting. In this article, the fundamental differences between spray forming and the other semisolid processes are discussed. Results show a unique thermal and solute profile on the deposit surface, resulting from the mixing of rapidly solidified metal formed during atomization and the solute-poor liquid formed by addition of the liquid of alloy composition, which contributes mainly to the microstructural evolution during spray forming. A simple experiment was designed to give supporting evidence to this view.

28 citations



Patent
06 Jun 2001
TL;DR: In this article, a method of spray forming a weldable metal deposit is described. The method comprises (a) providing a ceramic spray forming pattern, (b) heating the spray forming patterns to a sustained temperature sufficient to prevent internal stress formation in deposited carbon steel having a carbon content of less than about 0.3 weight percent when deposited on the heated spraying pattern, and (c) spraying metallic particles onto the spray spraying pattern heated to the sustained temperature, and allowing the sprayed metallic particles to cool to form a metal deposit.
Abstract: A method of spray forming a weldable metal deposit. The method comprises (a) providing a ceramic spray forming pattern, (b) heating the spray forming pattern to a sustained temperature sufficient to prevent internal stress formation in deposited carbon steel having a carbon content of less than about 0.3 weight percent when deposited on the heated spray forming pattern, (c) spraying metallic particles onto the spray forming pattern heated to the sustained temperature, and (d) allowing the sprayed metallic particles to cool to form a metal deposit. The metallic particles have a carbon content which is sufficient to result in metal particles having a carbon content of less than about 0.3 weight percent when deposited on the heated spray forming pattern. The resulting deposit has a carbon content of less than about 0.3 weight percent.

Journal ArticleDOI
TL;DR: In this article, the evolution of fine-grained microstructure during spray forming is a noteworthy feature and it is achieved by properly designed parameters such as the thermodynamic properties of the gas and the material and the important process variables like superheat temperature, gas pressure, metal flow rate and flight distance.
Abstract: The evolution of fine-grained microstructure, during spray forming is a noteworthy feature and it is achieved by properly designed parameters. These parameters include the thermodynamic properties of the gas and the material and the important process variables like superheat temperature, gas pressure, metal flow rate and flight distance. In the present investigation, fundamental characteristics of droplet dynamics and heat flow pattern have been analysed during the process. It has been indicated that the heat transfer coefficient at the droplet–gas interface is strongly influenced by the size of the droplets and their relative velocity with the gas stream. The droplet dynamics and the thermal state during deposition accordingly govern the microstructure evolution in the deposit. The solidification structure along peripheral to central regions of spray deposits, obtained using a spray atomization and deposition facility available at NPL in conical and flat disc shapes, has been evaluated. On the basis of preliminary observations, the analysis of process parameters during atomization and deposition and their consequences on the scale of microstructure in atomized droplets and spray deposits has been compared and discussed.

Journal ArticleDOI
TL;DR: In this article, the as-sprayed Cr 12 MoV steel has a relatively homogeneous and fine microstructure, which has a finer, more uniform carbide dispersion, and less segregation of Cr than the conventionally processed Cr 12MoV steel.



Journal ArticleDOI
TL;DR: In this paper, it is observed that a smaller deposition distance leads to large scale compositional inhomogeneity in the preform, which is attributed to increased incoming fraction of liquid at the deposition surface with growing thickness of the deposit.
Abstract: Spray forming of Al-18Si alloy and its behaviour in semi-solid state holding has been studies.It is observed that a smaller deposition distance leads to large scale compositional inhomogeneity in the preform. This effect is attributed to increased incoming fraction of liquid at the deposition surface with growing thickness of the deposit. A large liquid pool thickness leads to development of microstructure with a typical characteristics of conventional casting process. A uniform microstructure is evolved when the thickness of liquid pool is comparable to the thickness of the interaction domain formed during spray deposition.

Journal ArticleDOI
TL;DR: In this paper, the authors revisited the heat transfer analysis for the rapid solidification processing (RSP) of a metal droplet through two modelings with and without consideration of internal heat conduction, and two test problems with cooling rates of metal droplets of 107 and 103 K/s were studied.


Patent
20 Aug 2001
TL;DR: In this paper, a spray-formed article is created by spraying a plurality of metal streams upon a low-heat resistant model and thereby forming a spray formed article, where the spray conditions are controlled in such a manner that the individual metal droplets forming the metal streams remain substantially segregate.
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

Journal ArticleDOI
TL;DR: In this paper, the development of microstructure during spray forming of Al-Cu alloys is discussed in light of the solidification behaviour of droplets and spray-deposits.
Abstract: Spray forming exhibited an equiaxed grain morphology of the primary α-phase in Al–4.5 Cu alloy, round to irregular non-dendritic morphology of the primary α-phase in Al–15 Cu alloy, particulate eutectic morphology in Al–33 Cu alloy and non-faceted growth morphology of the primary CuAl2 β-phase in Al–40 Cu alloy. Development of microstructure during spray forming of Al–Cu alloys is discussed in light of the solidification behaviour of droplets and spray-deposits.

Patent
30 Jan 2001
TL;DR: In this article, a sputtering target is manufactured by adjusting the ratio of the gas flow volume (Nm 3 )/molten liquid flow mass (kg) to 5 Nm 3 /kg or more in the gas atomizing step of the spray forming method using an Al or Al alloy sputtering targets.
Abstract: The sputtering target is manufactured by adjusting the ratio of the gas flow volume (Nm 3 )/molten liquid flow mass (kg) to 5 Nm 3 /kg or more in the gas atomizing step of the spray forming method using an Al or Al alloy sputtering target material in which the maximum length of all the inclusions is 20 μm or less.

Journal Article
TL;DR: In this paper, the recent development of Cu Cr contact materials for high power vacuum interrupters is concluded, including the origination of the Cu Cr alloy and technical advantages, the characteristic of the CU Cr binary diagram and the difficulties in convenient casting process, the main preparation processes of the CA alloy, such as powder sinter, sinter and vacuum infiltrate and arc melting process, and the influence of impurities such as residual gases, residual carbon and the third element in CA alloy on the properties of CA alloy etc.
Abstract: The recent development of Cu Cr contact materials for high power vacuum interrupters is concluded. It includes the origination of Cu Cr alloy and technical advantages; the characteristic of Cu Cr binary diagram and the difficulties in convenient casting process; the main preparation processes of Cu Cr alloy, such as powder sinter, sinter and vacuum infiltrate and arc melting process; the influence of impurities, such as residual gases, residual carbon and the third element in Cu Cr alloy, on the properties of Cu Cr alloy etc. Also, it summarizes the effect of Cu Cr alloy and its microstructure on the basic electrical properties of the vacuum contactor (such as circuit interruption ability, resistance to erosion by arc, current chop etc.). Finally, the developing direction of the Cu Cr contact materials in the future (Cr particle dispersion, alloy recycle and qui fast solidification process, and spray forming etc.) are also discussed.

01 Jan 2001
TL;DR: In this paper, the microstructural characteristics and mechanical properties of Al-6.5Si and Al-18Si alloys have been investigated using spray-deposited and hot extruded at 480C with an area reduction ratio of 6:1.
Abstract: The microstructural characteristics and mechanical properties of Al–6.5Si and Al–18Si alloys have been investigated. The alloys were spray-deposited and hot extruded at 480C with an area reduction ratio of 6:1. The microstructure of the spray-deposit of Al–6.5Si alloy showed spherical morphology of the primary a-phase with a globular shape of the eutectic Si phase in the inter-particle boundaries. On the other hand, a fine particulate morphology of primary Si phase uniformly dispersed in the matrix of the a-phase was observed in spray-deposit of Al–18Si alloy. Microstructural refinement was further increased in the hot extruded alloys. The room temperature tensile tests of spray formed and extruded alloys showed considerable increase in their strength and ductility over that of the as cast alloys. The improvement in mechanical properties of spray formed alloys is discussed in light of the microstructural modifications induced during spray deposition process.

Journal ArticleDOI
TL;DR: In this article, microstructural features of atomized powders and spray-deposited preforms were evaluated by scanning and transmission electron microscopy and X-ray diffractometry techniques.
Abstract: An inert gas atomization process was employed in production of rapidly solidified powders as well as disc-shape preform by spray deposition of an Al75Mn10Cr5Si10 alloy. Microstructural features of atomized powders and spray deposited preforms were evaluated by scanning and transmission electron microscopy and X-ray diffractometry techniques. Solidification structure of powders revealed cellular and dendritic morphology, depending on their size. The interdendritic regions consisted of second phase particles. In contrast the spray formed alloy exhibited microstructural homogeneity with distribution of ultra-fine second phase particles of intermetallic compound. The structure of second phase intermetallics was identified as a cubic α-Al(Mn,Cr)Si, in both the atomized powders and the spray-deposits. The formation of cubic phase is discussed as rational approximant structure of an icosahedral quasicrystal.

01 Jan 2001
TL;DR: In this article, high strength Al-Zn-Mg-Cu alloys were produced by spray forming process, and compacted by hot extrusion, and the results show that the as-deposited billets have fine-grained microstructure and low porosity.
Abstract: High strength Al-Zn-Mg-Cu alloys were produced by spray forming process, and compacted by hot extrusion. The results show that the as-deposited billets have fine-grained microstructure and low porosity. After heat treatment, mechanical properties increase greatly: tensile strength up to 754 MPa, yield strength up to 722 MPa, fracture elongation up to 8%, and elastic modulus up to 72 GPa, respectively.

01 Mar 2001
TL;DR: Vacuum Plasma Spray (VPS) has been developed to reduce the cost and fabrication time of metal and ceramic rocket engine components as mentioned in this paper, but the difficulty of forming these materials into complex shapes has limited their application in the past.
Abstract: : Vacuum Plasma Spray techniques (VPS) have been developed to reduce the cost and fabrication time of metal and ceramic rocket engine components. Refractory metals and ceramics such as Re, Hf, W, W/Re, HfC, and HfN are being used for their high melting temperatures and chemical stability. However, the difficulty of forming these materials into complex shapes has limited their application in the past. The VPS technique involves spraying material onto a mandrel of the desired shape and subsequently removing the mandrel. A primary advantage of VPS forming over other powder metallurgy techniques is that near-net-shape spray forming of components significantly simplifies and reduces the cost of fabrication due to the high material utilization and reduction of laborious machining. Rocket nozzles have been fabricated and successfully tested in advanced applications with zero erosion. Standard metallurgical techniques have been used to characterize the effect of processing parameters on the microstructure of spray formed deposits. The deposited materials have high density with fine grain microstructures.

Patent
27 Nov 2001
TL;DR: In this paper, a method for implementing post-heat treatment during spray forming to achieve stress control in the manufacture of a spray formed metallic tool involves applying a metallic spray-forming material onto a mold substrate and causing substantially homogenous metallic phase transformations from the austenite phase, for example, via manipulation of either or both of the substrate temperature and the spray forming cell environment temperature.
Abstract: A method for implementing post-heat treatment during spray forming to achieve stress control in the manufacture of a spray formed metallic tool involves applying a metallic spray-forming material onto a mold substrate and causing substantially homogenous metallic phase transformations from the austenite phase, for example, via manipulation of either or both of the substrate temperature and the spray forming cell environment temperature.

Journal ArticleDOI
TL;DR: In this article, the potentials of spray forming in the field of flat and sheet metals and the examination of the workability in subsequent manufacturing of such products are examined. But the work in this paper is restricted to flat products, as well as problems with the production of a geometry suitable for subsequent treatment.

01 Jan 2001
TL;DR: In this paper, a very homogeneously formed microstructure of a ball bearing steel (100Cr6) and a high-speed steel (HS6-5-2C) was shown to avoid pores by high consolidation and the elimination of macro-segregations.
Abstract: Spray forming is known as a production procedure recently developed for technical materials, specially for the production of high-grade steels. The advantages of disintegration of the pouring into small droplets associated with rapid cooling leads to remarkable improvements of homogeneity by forming the primary microstructure in comparison to conventionally cast material. These goals are also found in all semi-finished products after thermo-mechanical treatments. Studies of the very homogeneously formed microstructure of a ball bearing steel (100Cr6) and a high-speed steel (HS6-5-2C) show also the avoiding of pores by high consolidation and the elimination of macro-segregations.