Showing papers on "Spray forming published in 2018"

Fabrication and Oxidation Resistance of TiAl Matrix Coatings Reinforced with Silicide Precipitates Produced by Heat Treatment of Warm Sprayed Coatings

Abstract: Ti-Al-based intermetallics are promising candidates as coating materials for thermal protection systems in aerospace vehicles; they can operate just below the temperatures where ceramics are commonly used, and their main advantage is the fact that they are lighter than most other alloys, such as MCrAlY. Therefore, Ti-Al-Si alloy coatings with five compositions were manufactured by spraying pure Ti and Al-12 wt.% Si powders using warm spray process. Two-stage hot pressing at 600 and 1000 °C was applied to the deposits in order to obtain titanium aluminide intermetallic phases. The microstructure, chemical composition, and phase composition of the as-deposited and hot-pressed coatings were investigated using SEM, EDS, and XRD. Applying of hot pressing enabled the formation of dense coatings with porosity around 0.5% and hard Ti5(Si,Al)3 silicide precipitates. It was found that the Ti5(Si,Al)3 silicides existed in two types of morphologies, i.e., as large particles connected together and as small isolated particles dispersed in the matrix. Furthermore, the produced coatings exhibited good isothermal and cyclic oxidation resistance at a temperature of 750 °C for 100 h.

Effects of hot extrusion and heat treatment on microstructure and properties of industrial large-scale spray-deposited 7055 aluminum alloy

Abstract: The industrial large-scale 7055 aluminum alloy fabricated by spray forming technology was subjected to hot extrusion and heat treatment to achieve high strength and ductility. Microstructure of the as-deposited alloy indicates that higher density billets with equiaxed grains (20–40 μm) were fabricated rather than a typical dendritic microstructure of the as-cast alloy. The grains of the as-extruded alloy exhibit fibrous morphology, the original boundaries disappear and fined second phases with size about 0.5–5 μm distribute along with extrusion direction. Meanwhile, the defects could be eliminated by hot extrusion, which resulted in good strength as well as ductility. The ultimate tensile strength, yield strength and elongation of the as-extruded alloy are 345 MPa, 236 MPa and 18.5%, respectively. After heat treatment, the partial recrystallization is observed around the un-recrystallized grains and sub-grains. And the platelet/rod-shaped precipitates (MgZn2) show a uniform distribution in the matrix alloy. The alloy reaches the maximum tensile strength of 730 MPa after T6 temper treatment, associated with a fine precipitation (MgZn2). However, with further deepen aging degree (from T6 to T73 temper), the size of dominant precipitated phases (MgZn2) grows obviously, the grain boundary precipitates transform from continuous to individual ones and the width of precipitate free zone increases. The result shows that the alloy after T7X temper treatment exhibits higher electrical conductivity (>35 %IACS) and facture toughness (>25.6 MPa m1/2) although a 8%–17% reduction in strength compared with that at T6 temper.

Aluminum lithium alloy for spaceflight and method for preparing proximate matter through aluminum lithium alloy

Abstract: The invention relates to an aluminum lithium alloy for spaceflight and an aluminum lithium alloy proximate matter preparing method, and relates to the aluminum lithium alloy and the aluminum lithium alloy proximate matter preparing method. The aim is to solve the problems that the production difficulty of the aluminum lithium alloy is large, and the aluminum lithium alloy strength is low. The aluminum lithium alloy is composed of Mg, Li, Ti, Zr and Al, the Mg accounts for 5.5%-6.5%, the Li accounts for 2.2%-2.5%, the Ti accounts for 0.03%-0.12%, the Zr accounts for 0.15%-0.20%, the Zr+Ti is smaller than or equal to 0.25%, and the balance is the Al. The method includes the steps of raw material weighing, aluminum alloy molten liquid preparing, refining, spray forming, short bar cutting, blind die extrusion, heat extrusion, quenching, tension leveling and aging treatment. According to the aluminum lithium alloy and the aluminum lithium alloy proximate matter preparing method, through spray forming, the problems that the aluminum lithium alloy production difficulty is large, and the quality is poor are solved, the strength of extension reaches 485 Mpa, the ruled non-proportional extending strength reaches 345 Mpa, the percentage elongation after fracture reaches 10.0%, and blind die extrusion enables a casting ingot to be more compact.

Cold and hot working die steel and manufacturing technology thereof

Abstract: The invention provides a manufacturing technology of cold and hot working die steel, and belongs to the technical field of die steel manufacturing. The manufacturing technology comprises the steps ofmedium frequency smelting, external refining, spray forming, first annealing, thermal deformation forging, second-time forging, residual heat annealing after forging, quenching and multiple tempering.According to the manufacturing technology, segregation of components in a steel ingot is restrained in a quite small range through the spray forming step, meanwhile, large particle carbide can be effectively prevented from being formed through two times of forging, the steel impact toughness and plasticity are improved, and the steel quality is improved. The invention further provides the cold and hot working die steel. The cold and hot working die steel comprises 0.55-0.65% of C, 0.85-1.15% of Si, 3.7-4.4% of Cr, 1.8-2.2% of Mo, 1.3-1.7% of V, 1.9-2.2% of W and the balance Fe and impurities.The cold and hot working die steel is uniform and small in structure, large particle carbide is prevented from existing, the die steel has high hardness and high impact toughness which can be equivalent with the toughness of powder steel, and meanwhile the die steel has good plasticity.

Characterisation of Plasma Sprayed CNT-Alumina Composite Coatings on Boiler Tube Steel

Abstract: In this research work, the 1.5, 2 and 4 wt.% CNTs-Al 2 O 3 coatings were prepared and successfully deposited on T22 boiler tube steel using plasma spray process. Ni-Cr was also used as bond coat before applying CNTs-Al 2 O 3 coatings. The coatings were subjected to metallography, XRD and SEM/EDAX analysis. The porosity of CNTs-Al 2 O 3 mixed coatings on T22 boiler steel was found to be decreasing with increase in CNTs content. The CNTs were found to be uniformly distributed within the Al 2 O 3 matrix. The CNTs were chemically stable during the spray forming and did not react to form oxides or aluminium carbides even at very high processing temperature. Cite this Article Rakesh Goyal, Buta Singh Sidhu, Vikas Chawla. Characterisation of Plasma Sprayed CNT-Alumina Composite Coatings on Boiler Tube Steel. Journal of Polymer & Composites . 2017; 5(3): 1–1 7 p.

Ultrahigh-strength aluminum alloy and preparation method thereof

Abstract: The invention provides an ultrahigh-strength aluminum alloy, which comprises 3.0-10.0wt% of Cu, 2.0-9.7wt% of Mg, 1.7-38wt% of Zn, 0.1-1.3wt% of Nd, 0.05-2wt% of Ni, 0.05-1.77wt% of Mn, 0.01-0.5wt% ofT and the balance of Al. The invention also provides a preparation method of the ultrahigh-strength aluminum alloy. According to the preparation method provided by the invention, an aluminum alloy material is prepared by adopting a specific formula and a spray forming process, the micro-structure of the aluminum alloy material is obviously refined, and the precipitated phase is fine and uniformlydistributed, so that the mechanical property of the aluminum alloy material is hardly anisotropic, and the aluminum alloy material has the advantages of high strength, high toughness, high rigidity and light weight. Experimental results show that after T6 treatment, the tensile strength of the ultrahigh-strength aluminum alloy provided by the invention is higher than or equal to 917MPa, and the yield strength is higher than or equal to 874MPa.

Production technique for spray forming composite TBM cutter ring

Abstract: The invention provides a production technique for a spray forming composite TBM cutter ring and belongs to the field of mechanical manufacturing and machining. The production technique comprises the steps of spray forming of a composite pipe blank, blanking, forging forming, annealing after forging, rough machining, quenching and tempering heat treatment, accurate grinding and the like. The cutterring formed through the production technique is a composite cutter ring, a low-alloy steel material which is high in anti-impact toughness and low in cost mainly plays a supporting role, and edge parts, used for rock breaking, of the cutter ring are made of a die steel material which is good in abrasion resistance and has certain anti-impact performance; a bimetal interface subjected to high-temperature one-time spray forming serves as a transitional area, metallurgical bonding is sufficient, metallurgical bonding strength is high, and using of alloy elements is reduced to a great extent while the cutter ring cost is lowered; and a series of high-energy-consumption metallurgical processes such as smelting, refining and electroslag remelting are omitted in the whole manufacturing technique, and the production technique is worth applying and popularizing.

Successive Spray Forming and Selective Heat Treatment of Composite Tool Steels

Abstract: In many metal forming applications, especially in micro cold forming, the tools are loaded differently in various functional regions. Tailored material properties in the specific regions a...

Spray forming and atomization powdering dual-purpose device

Abstract: The invention discloses a spray forming and atomization powdering dual-purpose device, which comprises a machine body, and a gas inlet is arranged in a spray chamber in the machine body. When a turntable is first close to a nozzle and then gradually rotated down, a metal spray formed body can be manufactured; meanwhile, metal droplets which are not formed also form metal powder, and when the turntable starts to move away from the nozzle, powdering can be well formed and a gate can be used for collecting metal powder. The spray forming and atomization powdering dual-purpose device in the invention is used for metal spray forming and manufacture of metal powder.

SYNTHESIS OF Mg-Cu-Y BULK METALLIC GLASS PLATE VIA SPRAY FORMING PROCESS

Abstract: Mg-based amorphous alloys exhibit maximum specific strength among bulk metallic glass systems. In this study, a bulk Mg65Cu25Y10 deposit was produced successfully via spray forming process with higher cooling rate than conventional mold casting route. The deposit is 300mm in diameter, 10 mm in thickness and 650 g in weight. The average porosity is about 10%. The XRD and DSC results of the deposit look similar to that obtained from corresponding amorphous melt-spun ribbon. However, the measured composition of deposit varies slightly with the distance from substrate, which attribute to gravity effect of relative heavy element, like Y and Cu. The hardness of the deposit is higher than that of melt spun ribbons. The supercooled liquid region of the deposit determined from TMA technique is about 20K smaller than that obtained from DSC trace due to the stress induced nanocrystallzation occurred in the former. In addition, the volume reduction of deposit during TMA test was also smaller than that of ribbon and shows better dimension stability.

Microstructure and Mechanical Properties of Spray Formed and Hot Pressed/HeatTreated Al-(20-30 wt%) Mg2Si-2% Cu Alloy

Abstract: In the present investigation, Al-(20-30%wt) Mg2Si-2Cu alloys were synthesized by spray forming process and further processed by hot pressing for densification. The alloys were further subjected to age hardening heat treatment. The spray formed, age hardened and as-cast alloys were characterized by microstructure and mechanical properties. The microstructure of spray formed alloys exhibited finer and evenly distributed primary β-Mg2Si particles and θ-Al2Cu phase and clusters of discrete and high volume fraction of Q-phase. As-cast alloys mainly consist of large sized polygonal primary β-Mg2Si, coarse Chinese script of Al2Cu and needle shaped eutectic Q-phase. Hot pressing of the spray formed alloy promotes the microstructural refinement, reduction in porosity, fragmentation and redistribution of secondary phases. Artificial age hardened alloys exhibits the large quantity of θ-Al2Cu precipitates less than 2 μm size uniformly distributed in the matrix. The β phase re-precipitates in a very fine spherical form results in an increase in the area fraction of β-Mg2Si phase during aging. The significant enhancement in ultimate strength in heat treated and sprays formed alloys as compared to the as-cast alloy. The SEM of fracture surfaces of tensile specimens was taken on spray formed age hardened and as cast alloys. The fractographs revealed the transformation from brittle mode to ductile dimples.

Precision spray formed metal tube and manufacturing method thereof

Abstract: The invention discloses a precision spray formed metal tube and a manufacturing method thereof, and belongs to the technical field of mechanical manufacturing. The precision spray formed metal tube comprises a metal inner tube, an adhesion layer is evenly sprayed on the circumferential outer wall of the metal inner tube, and a metal jet layer is evenly sprayed on the outer surface of the adhesionlayer. According to the precision spray formed metal tube and the manufacturing method thereof, vertical precision spray forming is adopted, meanwhile, the bottom of a clamp has a rotating function, aworkpiece autorotates while a spraying gun sprays, spraying on the surface of the workpiece is even, and the manufacturing precision is high; and the production cost is reduced, the production efficiency is improved, and the formed metal tube is high in hardness, good in mechanical performance, and excellent in abrasion-resistant performance.

Device for rapidly manufacturing mould through spray forming, and method for manufacturing mould

Abstract: The invention relates to a device for rapidly manufacturing a mould through spray forming, and a method for manufacturing the mould. The device comprises a cavity, an induction smelting furnace, a tundish, an atomization spraying mechanism, a whole of a ceramic receiver and a heating device, a three-dimensional oblique rotating device, a lifting device, an axial compression device, an inert gas quenching device, a plurality of operating handles and operating gloves. The method comprises the steps that spray-formed tool and mould steel on the surface of the ceramic receiver is axially compressed in the cavity, holes are completely eliminated, and the surface geometrical morphology and smooth finish of the ceramic receiver are completely replicated; when a cooling pipeline is placed in or the mould does not contain the cooling pipeline, the axially compressed tool and mould steel is subjected to direct gas quenching in the cavity into of a martensite structure, the outer profile is machined outside the cavity, and tempering is conducted; and after axial compression, the tool and mould steel can also be removed from the cavity to be annealed, the cooling pipe and the outer profile aremachined, and quenching and tempering are conducted. The holes in the mould can be reliably and thoroughly eliminated, and the completely accurate mould cavity is obtained.

Binder-free spray forming technology for improving molecular sieve catalyst strength

Abstract: The invention belongs to the technical field of catalysts, and particularly relates to a binder-free spray forming technology for improving the molecular sieve catalyst strength. The technology comprises the following steps that 1, dispersant is added in deionized water to form a dispersant solution, a molecular sieve catalyst is added in the dispersant solution, and slurry with the solid contentbeing 35-50% is formed; 2, an agate ball is added in the slurry, ball milling is conducted for 2-6 h, sieving is conducted, the agate ball is separated, and the separated slurry is preserved at the constant temperature of 25 DEG C; 3, the slurry obtained in step 2 is subjected to spray drying forming; 4, a product obtained in step 3 is dried in an air atmosphere of 100-150 DEG C, and then roastingis conducted. According to the forming technology, the abrasive resistance of the catalyst is improved, and on the condition that a binder is not added, the high abrasive resistance can still be kept.

Microstructure and Mechanical Properties of Aluminum Alloy with Ultra-high Strength Prepared by Spray Forming

Abstract: In this paper, Al–11Zn–3Mg–2Cu–0.2Zr alloy was prepared by spray-forming, and then it was treated by defect reduction, hot worked and heat treatment. Microstructure and mechanical properties of the aluminum alloy were researched during the whole processing by metallographic microscope, scanning electron microscope (SEM), and tensile test. Average grain size of spray-formed aluminum alloy was about 10–20 μm due to the high cooling rate closing 1000 K/s, and shrinkage porosity and cavity was inevitable in spray-formed ingot because of nitrogen as carrier. Through hot isostatic pressing and hot extrusion, the relative density increased from 87– 90% to almost 99–100%, but it decreased again to about 98% after solution, which meant some porous defects could not be eliminated thoroughly. Comparing with casting, the original grain of spray-formed ingot was much smaller, which was unsuited for plastic processing with large deformation. A large plastic deformation caused lots of recrystallization, which weakened the mechanical properties. In the areas without defects, the best properties of the spray-formed alloy were 825 MPa in tensile strength, 808 MPa in yield strength, and 9% in elongation.

Precision-molding method for metal part additive

Abstract: The invention discloses a precision-molding method for a metal part additive. The method comprises the following steps: step 1, dividing the surface of a metal part into a surface to be processed anda non-machined surface, and manufacturing a casting mold corresponding to the non-machined surface, wherein the casting mold is manufactured by 3D printing and molding; step 2, by adopting a uniform metal droplet ejection technology, spraying metal droplets to a bottom plate of the casting mold layer by layer through a nozzle until the spraying is completed; step 3, molding, standing and cooling,demoulding and cleaning a molded part. According to the invention, by combining the casting mold through 3D printing and the uniform metal droplet spray forming technology, the metal part can be directly precision-molded, and the dimensional accuracy, surface quality, internal quality and quality stability of the molded metal part are high than those by traditional casting methods.

Substituting steel type of cobalt containing high-speed steel

Abstract: The invention discloses a substituting steel type of a cobalt containing high-speed steel. The steel type comprises following components in percentage by weight: 1.0 to 2.5% of C, 0.72 to 2.0% of Si,0.31 to 1.5% of Mn, 4.0 to 8.0% of Cr, 5.5 to 10.0% of Mo, 2.0 to 9.0% of V, and 2.0 to 10.0% of W. The steel type has the advantages that super speed solidification of spray forming is used to improve the solid dissolving performance of alloy elements such as Mo, V, W, Si, and the like so as to replace the solid dissolution enhancing effect of Co on high-speed steel matrix and carbides and high temperature stability; at the same time, Si is used to eliminate the adverse effect caused by high contents of Mo, V, and W; economic components are used to reach or exceed the use performance and service life of cobalt containing high-speed steel, and the method is sued to prepare high performance high-speed steel.