Transition metal aluminide coatings and initial steps on. A preliminary investigation of platinum modified aluminide coatings from two. Zirconium modified aluminide coatings obtained by the cvd and. The cast platinum aluminide coating composition exhibited poor hot corrosion and oxidation resistance relative to crcontaining and hfdoped nial, respectively. Pack aluminide coatings were performed on a tialcrnb alloy doped with zirconium and yttrium having two phase of a 2ti 3 al and gtial microstructure. In essence, the present results on cast aluminides indicated that hot corrosion resistance and exceptional scale spallation resistance appears to be mutually incompatible goals for. At byron products our process working zone is approximately 36 in height and 44 in diameter. Phase composition of the investigated coatings was made using arl xtra x ray di. A method of forming a platinum modified diffusion aluminide coating on a substrate, comprising depositing a layer comprising platinum on the substrate, disposing the substrate in a coating chamber having a solid source comprising aluminum therein, wherein said substrate and said solid source are disposed so proximate one another as to form on said substrate at an elevated. Aluminide and platinum modified aluminide coatings have proven to be effective and.
Aluminide coating formation on nickelbase superalloys by pack cementation process article in journal of materials science 3623. Formation of an aluminide coating on hot stamped steel. Magnesium aluminide is an intermetallic compound of magnesium. Slurry aluminide coatings were produced on tibased alloy ti6al4v in an argon atmosphere. Conventional and platinum modified diffusion aluminide coatings on some stateoftheart single crystal and polycrystalline nickelbase superalloys have been compared n tests designed to establish conditions representative of those existing in gas turbines operating over a range of applications. The outer bright layer visible in figure 6 is the nip coating deposited in order to protect the aluminide coating during metallographic sample preparation. When pure aluminum was used as the aluminum source, 80125. Composition, and oxidation resistance of aluminide coatings. Semtem investigation of aluminide coating codoped with pt. The microstructures were characterised by analytical electron microscopy, scanning electron microscopy and x. Others also require an external thermal barrier coating to be applied over an underlying bond coating containing aluminides. The effects of different substrate surface roughness and aluminizing agent composition on the coating surface roughness, phase structure and the thickness of each phase in the coating were studied. One of the major problems faced by aluminide coatings is thermomechanical fatigue, as cyclic strains induced by temperature gradients in the blades can lead to thermal. The structure and composition of the coating depends on the substrate, implying that coatings must be tailored for a given alloy.
Schutze, corrosion and environmental degradation vol. Virtually any material that can alloy with aluminum can be coated with this procedure. The coating structure and composition have been characterized and the cyclic oxidation and hot corrosion properties have been evaluated for the different types of coatings. The mediumsize gasturbine engines typified by mediumrange commercial aircraft propulsion are making extensive use of directionally solidified and singlecrystal high. Mechanisms of formation of diffusion aluminide coatings on. Therefore in this paper, the influence of rhodium on the microstructure and phase composition of aluminide diffusion coatings deposited on the nickel substate and cmsx 4 nibased superalloy by the cvd metod is analysed. Further improvements can be achieved by the use of platinum in these coatings 1, although the mechanisms by which platinum achieves this is still uncertain 2. Liquid coating technology wet, which has been applied for more than two centuries powder coating technology dry, which has been applied on an industrial scale for some 30 years. Graded platinum diffusion aluminide coating howmet research. The global average annual growth for powder coatings has been approximately 79% over the last 10 years. Part of the nato asi series book series nsse, volume 85 nickel and cobalt superalloys currently used in advanced gas turbines are almost always protected by coatings against high temperature oxidation and hot corrosion. Role of platinum in aluminide coatings sciencedirect.
Recent progress in the coating protection of gamma. Hafnium was found in the additive nial layer of aluminide coating deposited. Hightemperature coatings for superalloys can be divided into three categories. This method enables a simple modification of chemical composition of the coating through addition of different powders. The aluminide coating made in process with the parameters of t1,050 c, t8 h and p150 hpa had thickness of 3040. The first type is formed by inward diffusion of aluminum. Platinum in aluminide diffusion coatings johnson matthey. High purity, submicron and nanopowder forms may be considered. The fib technique is suitable for gathering complete details of the internal composition of the individual layers of the coating, and also of other coatings and general surface treatments. The formation of an aluminide coating prior to hot stamping was investigated as a method to simultaneously improve the coating ductility and achieve a good hot corrosion resistance of the hot stamped parts. A method of forming a platinum modified diffusion aluminide coating on a substrate, comprising depositing a layer comprising platinum on the substrate, disposing the substrate in a coating chamber having a solid source comprising aluminum therein, wherein said substrate and said solid source are disposed so proximate one another as to form on said substrate at an elevated coating. Those imc coating materials of interest rely on aluminide, chromide or silicide intermetallics because they can form protective oxide films of al 2 o 3, cr 2 o 3 or sio 2 1, 2, 3.
Platinummodified diffusion aluminide coatings on nickel. Chemical composition of superalloys is presented in table 1. An evaluation study of aluminide and chromoaluminide coatings. Coatings free fulltext the influence of aluminizing. Studies on microstructures and compositions of model diffusion aluminide coatings coupled with existing information on diffusion in nickelaluminum intermetallic compounds indicate that only two basic types of these coatings can be formed on nickelbase superalloys. The platinum modified aluminide coating has better oxidation resistance than nonmodified and palladium. From country to country worldwide these figures have. The effects of niplating and prolonged high temperature oxidation at 1423 k 1150 c on a cmsx10 singlecrystal nibased superalloy and coating system initially, the as aluminized coating was 31 lm thick, but oxi dizing the system for 188 hours produced a coating that was 81 lm thick. Hi achmadarifudinh sermaloy j slurryapplied aluminide diffusion slurry coating and sermaloy j cf diffusion aluminide slurry coating, both are metallic ceramic coatings, and had a final color result from light grey to dark green and is possible to obtain a variety of colors within this range, changing kind of slurry, purity of the oven gas or the oven parameters like time pressure and. Microstructures and phase compositions of coatings obtained by different methods differ significantly. Bates et al 16 studied the effects of different aluminum sources on aluminide coatings. Platinumaluminide coatings were applied to polycrystalline, directionally solidified and singlecrystal superalloy rods before they were oxidised in still air at temperatures of and 1100c. Coatings for high temperature applicationsbond coats.
The easiest way is by cospraying the elemental powders or ballmilled powders with a solid solution composition, thus avoiding the challenges of the high strength and brittleness of the intermetallic compound. Oct 22, 2001 a multiyear effort has been focused on optimizing the longterm oxidation performance of ingotprocessed ip and oxidedispersion strengthened ods fesub 3al and iron aluminide based coatings. In spite of good oxidation resistance of the rhodium modified aluminide coating, mechanism of its formation is unknown. Nickel aluminide ni 3 al is an intermetallic alloy of nickel and aluminium with properties similar to both a ceramic and a metal. Further improvements can be achieved by the use of platinum in these coatings 1, although the mechanisms by which platinum achieves. It is characterized by relatively low costs of its realisation and necessary equipment. The results showed that hafnium accumulates mainly on diffusionadditive layer interface and forms a chain of small precipitations. Platinum aluminide cvd coating method howmet research. Part of the nato asi series book series nsse, volume 85. E manufacturing technologies of coating processes coatings.
Aluminide coatings have an ability to form a protective and slowly growing. Nial, cas number 12003780 see also raney nickel nial 3, cas number 12004716. The properties of the aluminide coating depend on the process methodologies used to deposit the coating, the substrate composition. Structure of pdzr and ptzr modified aluminide coatings deposited by a cvd method on nickel superalloys article pdf available in kovove materialy 5705. Coatings for turbine blades possess some attractive properties like oxidation and hot corrosion resistance, maintain their strength, cohesion and etc. Full text of thermodynamics and kinetics of pack aluminide. Commercially prepared aluminide coatings on hastelloy x and rnconel 617. Platinum aluminide coatings johnson matthey technology. Coatings for high temperature applicationsbond coatsmcraly. The structure and the composition of an aluminide coating varies for di. Chemical composition was analyzed using eds method. Results and discussion the surface area of the deposited coating was tight and uniform in aspect of chemical composition fig 2 a. Effect of the platinum electroplated layer thickness on the coatings. After 1,000 1h cycles, a massive oxide scale was formed with a complex oxide composition and a porous microstructure.
The aluminide coating made on the superalloy inconel 625 in the lowactivity cvd process with the parameters of t1,020 c, t4 h and p150 hpa had thickness of 3537. During high activity aluminization a change occurs in the surface platinum composition and structure. The effect of simultaneous introduction of hf and pt into aluminide coating deposited on inconel 625 alloy was investigated using scanning and transmission electron microscopy semtem methods. Diffusion coatings for hightemperature applications on ni. Based on results from several composition iterations, a hfdoped alloy fe28al2cr0. Vapor phase aluminide coatings this type of aluminide coating is also referred to a vpa, abovethepack, and gasphase aluminide. High temperature corrosion type ii 600850c, high temperature corrosion type i 750950c, oxidation 950c and higher. The high activity tial 3based coating was developed from aluminizing process carried out at 850c for 25 hours in a pack containing 20%wt al, 2%wt nh 4 cl, and 78%wt al 2 o 3. Corrosion testing of slurry aluminide coatings in molten. The present investigation is mainly concerned with the development of both aluminide and chromoaluminide coatings on in100, a cast nibase superalloy. Manganese aluminide is generally immediately available in most volumes.
The composition of the mixtures has an important influence on the aluminide coating. A after l200hrs of beat treatment at 00 d calculated after astn hand book. Influence of deposition process parameters on adhesive properties of ceramic top coat 9783659412189. The fib technique is suitable for gathering complete details of the internal composition of the individual layers of the coating, and also of. The degradation of type 1 aluminized coating during hot stamping leads to the coating cracking due to the formation of a brittle feal 2 intermetallic phase. Hafnium was found in the additive nial layer of aluminide coating deposited on in100 superalloy. Hi achmadarifudinh sermaloy j slurryapplied aluminidediffusion slurry coating and sermaloy j cf diffusion aluminide slurry coating, both are metallic ceramic coatings, and had a final color result from light grey to dark green and is possible to obtain a variety of colors within this range, changing kind of slurry, purity of the oven gas or the oven parameters like time pressure and. The microstructures were characterised by analytical electron microscopy, scanning electron microscopy and xray diffraction. Figure 9a shows a cross section sem micrograph indicating rapid oxidation of a poorly processed aluminide coating acting as a bond coat for an ebpvd thermal barrier top coating.
The microstructure and composition of a coating depend on the rate at which alloying elements such as chromium, molybdenum, and tungsten of the superalloy segregate in the coating. The aluminisation process is performed on steels 244,246,247,269273, superalloys 274281, nonferrous metals 282284, etc. The obtained coatings were examined by the use of an optical microscope microstructure and coating thickness a scanning electron microscope chemical composition on the crosssection of the modified aluminide coating and xrd phase analysis. Transition metal aluminides as bulk materials are seen as potential candidates for future substitution of superalloys since they can also offer significant. The oxidation and hot corrosion resistance of high temperature nickelbase superalloy components can be improved by aluminide coating.
A slurry with a newlydeveloped composition was applied, consisting of. Aug 19, 1997 a platinum modified aluminide coating of relatively uniform thickness which incorporates the existing engine run simple aluminide coating can be produced by first platinum plating the entire gas path surface area of the airfoil 9 to 10 gramscm 2 pt layer, then aluminizing that area with a cvd outward growth process of the type described to. The thickness of aluminide coating at 900c was about 110. Conclusions platinum in aluminide coatings on nickelbased super alloys is found 1 to increase the coating stability towards inward diffusion of aluminium or outward diffusion of nickel, 2 to eliminate chromiumrich pre cipitates from the outer coating layers and 3 to prevent refractory transition elements such as molybdenum, vanadium. The value for the radiationsynthesized coating locates at the lower limit side close to that of superior ptal coatings. The microstructure and oxidation resistance of the. Due to its unique properties related to its place in group three of the periodic table, aluminum can bond with metals differently than other metals, forming intermetallic compounds with properties between a metallic alloy and an ionic compound.
Results show that the main phase of the aluminide coatings was nial. Typical mcraly bond coats mfe,co or ni contain at least 4 elements, which means that coating methods such as pack cementation are considerably more difficult to use, as the activity of each element in the pack would have to be controlled carefully so as to obtain a coating of required composition. The morphology and composition of a coating are functions of the pack. The rhodiummodified aluminide coating b has better oxidation resistance. Aluminide compounds contain aluminum and one or more electropositive elements. Some properties of platinum and palladium modified aluminide. Influence of substrate composition on the oxidation performance of. The aluminide coating can be formed at lower temperature due to the addition of rare earth oxide in the mixture powders. Thermal barrier coating on gamma titanium aluminide by ebpvd. The oxidation resistance of aluminide coating is contributed to the formation of a continuous thermally grown oxide, predominantly. A platinum modified aluminide coating of relatively uniform thickness which incorporates the existing engine run simple aluminide coating can be produced by first platinum plating the entire gas path surface area of the airfoil 9 to 10 gramscm 2 pt layer, then aluminizing that area with a cvd outward growth process of the type described to. The silicon enriched nickel aluminide diffusion coating was ion milled using the focused ion beam fib technique figure 4. Aluminide coating formation on nickelbase superalloys by.
Superalloys source book, american society for metals, 1984. Aluminide coating single crystal superalloy external zone high temperature oxidation. The line profiles illustrating the distribution of elements in the crosssection of the coating figure 7 indicate that in comparison to the substrate alloy, it is enriched in al and. A multiyear effort has been focused on optimizing the longterm oxidation performance of ingotprocessed ip and oxidedispersion strengthened ods fesub 3al and iron aluminidebased coatings.
The first type is formed by inward diffusion of aluminum from coating media of sufficiently high aluminum activity to cause. Aluminide coatings are generally obtained by low or high activity pack cementation processes. Two of them, diffusion and overlay coatings, are both used to protect a system from oxidation and corrosion. Aluminides are compounds containing aluminum and one or more electropositive elements.
It is reported that pt facilitates outward diffusion of al in aluminide phase and pt doping in alumina scale lowers its growth 8,9,18,19. Aluminide diffusion coatings are classically deposited from a powder cement composed of an activator nh 4cl, a metallic donor al and an inert filler al 2o 3 262268. Optimum coating composition in relation to oxidation and hotcorrosion resistance, after m. Microstructure of aluminide coatings on ti6al4v alloy. Sep 16, 2015 the silicon enriched nickel aluminide diffusion coating was ion milled using the focused ion beam fib technique figure 4. High temperature corrosion behavior of iron aluminide alloys. See other formats component part mot ice this paper is a component part of the following compilation report. The third type, thermal barrier coatings, protects the substrate from thermal degradation. Limited mcraly usually ebpvd and some ebpvd tbcs are now in use. Compatibility of aluminidecoated hastelloy x and inconel 617 in a. Gas turbine component coating systems hitech furnace. Aluminide and platinummodified aluminide coatings are widely used pack or cvd if machined after coating. Yttrium aluminium garnet yag, y 3 al 5 o 12 is a synthetic crystalline material of the garnet group.
High temperature damages divide in three general groups. Effects of substrate surface roughness and aluminizing agent. Top american libraries canadian libraries universal library community texts project gutenberg biodiversity heritage library childrens library. The chemical composition of these coatings are adjusted to be compatible with the parent alloys and to meet the particular oxidation or. Structural property effects for platinum modified aluminide coatings. Synthesis of advanced aluminide intermetallic coatings by low. The heat of formation vs composition curve features maxima of about 25 k. It is a cubic yttrium aluminium oxide phase, with other examples being yalo 3 yap in a hexagonal or an orthorhombic, perovskitelike form, and the monoclinic y 4 al 2 o 9 yam. Structure of platinum modified aluminide coatings springerlink. Metals free fulltext rhodium and hafnium influence on the.
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