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. An evaluation study of aluminide and chromoaluminide coatings. Mechanisms of formation of diffusion aluminide coatings on. The properties of the aluminide coating depend on the process methodologies used to deposit the coating, the substrate composition. Part of the nato asi series book series nsse, volume 85. The heat of formation vs composition curve features maxima of about 25 k.
The aluminide coating made in process with the parameters of t1,050 c, t8 h and p150 hpa had thickness of 3040. 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. When pure aluminum was used as the aluminum source, 80125. Hafnium was found in the additive nial layer of aluminide coating deposited on in100 superalloy. 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. The present investigation is mainly concerned with the development of both aluminide and chromoaluminide coatings on in100, a cast nibase superalloy. Results and discussion the surface area of the deposited coating was tight and uniform in aspect of chemical composition fig 2 a. Synthesis of advanced aluminide intermetallic coatings by low. E manufacturing technologies of coating processes coatings. Schutze, corrosion and environmental degradation vol. 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. The outer bright layer visible in figure 6 is the nip coating deposited in order to protect the aluminide coating during metallographic sample preparation. The mediumsize gasturbine engines typified by mediumrange commercial aircraft propulsion are making extensive use of directionally solidified and singlecrystal high. In spite of good oxidation resistance of the rhodium modified aluminide coating, mechanism of its formation is unknown.
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. The value for the radiationsynthesized coating locates at the lower limit side close to that of superior ptal coatings. 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. 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. Vapor phase aluminide coatings this type of aluminide coating is also referred to a vpa, abovethepack, and gasphase aluminide.
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. 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. Transition metal aluminide coatings and initial steps on. Composition, and oxidation resistance of aluminide coatings. The composition of the mixtures has an important influence on the aluminide coating.
From country to country worldwide these figures have. 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. At byron products our process working zone is approximately 36 in height and 44 in diameter. Influence of substrate composition on the oxidation performance of. 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. 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 and platinum modified aluminide coatings have proven to be effective and. 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. The structure and the composition of an aluminide coating varies for di. The first type is formed by inward diffusion of aluminum. Hightemperature coatings for superalloys can be divided into three categories. 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.
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 compounds contain aluminum and one or more electropositive elements. Aluminide coating formation on nickelbase superalloys by pack cementation process article in journal of materials science 3623. A preliminary investigation of platinum modified aluminide coatings from two. Influence of deposition process parameters on adhesive properties of ceramic top coat 9783659412189. 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. 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.
The results showed that hafnium accumulates mainly on diffusionadditive layer interface and forms a chain of small precipitations. 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. 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. 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. The microstructure and oxidation resistance of the. 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. Aluminide coating formation on nickelbase superalloys by.
Coatings for turbine blades possess some attractive properties like oxidation and hot corrosion resistance, maintain their strength, cohesion and etc. High purity, submicron and nanopowder forms may be considered. Semtem investigation of aluminide coating codoped with pt. The thickness of aluminide coating at 900c was about 110. The cast platinum aluminide coating composition exhibited poor hot corrosion and oxidation resistance relative to crcontaining and hfdoped nial, respectively. Aluminide coatings are generally obtained by low or high activity pack cementation processes. The microstructures were characterised by analytical electron microscopy, scanning electron microscopy and x. Aluminide and platinummodified aluminide coatings are widely used pack or cvd if machined after coating. Manganese aluminide is generally immediately available in most volumes. Platinummodified diffusion aluminide coatings on nickel. Coatings for high temperature applicationsbond coatsmcraly. Commercially prepared aluminide coatings on hastelloy x and rnconel 617. Coatings for high temperature applicationsbond coats.
Recent progress in the coating protection of gamma. Slurry aluminide coatings were produced on tibased alloy ti6al4v in an argon atmosphere. Platinum in aluminide diffusion coatings johnson matthey. Virtually any material that can alloy with aluminum can be coated with this procedure. Some properties of platinum and palladium modified aluminide. The oxidation resistance of aluminide coating is contributed to the formation of a continuous thermally grown oxide, predominantly. Bates et al 16 studied the effects of different aluminum sources on aluminide coatings. Transition metal aluminides as bulk materials are seen as potential candidates for future substitution of superalloys since they can also offer significant. High temperature damages divide in three general groups.
Zirconium modified aluminide coatings obtained by the cvd and. Formation of an aluminide coating on hot stamped steel. Further improvements can be achieved by the use of platinum in these coatings 1, although the mechanisms by which platinum achieves. Hafnium was found in the additive nial layer of aluminide coating deposited. Results show that the main phase of the aluminide coatings was nial. The first type is formed by inward diffusion of aluminum from coating media of sufficiently high aluminum activity to cause.
Graded platinum diffusion aluminide coating howmet research. Platinum aluminide cvd coating method howmet research. The platinum modified aluminide coating has better oxidation resistance than nonmodified and palladium. Platinum aluminide coatings johnson matthey technology. This method enables a simple modification of chemical composition of the coating through addition of different powders. Top american libraries canadian libraries universal library community texts project gutenberg biodiversity heritage library childrens library. 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 third type, thermal barrier coatings, protects the substrate from thermal degradation. Effects of substrate surface roughness and aluminizing agent. 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. A slurry with a newlydeveloped composition was applied, consisting of. 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. Effect of the platinum electroplated layer thickness on the coatings. The chemical composition of these coatings are adjusted to be compatible with the parent alloys and to meet the particular oxidation or.
The oxidation and hot corrosion resistance of high temperature nickelbase superalloy components can be improved by aluminide coating. Coatings free fulltext the influence of aluminizing. Magnesium aluminide is an intermetallic compound of magnesium. 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. Chemical composition of superalloys is presented in table 1. Sep 16, 2015 the silicon enriched nickel aluminide diffusion coating was ion milled using the focused ion beam fib technique figure 4. The global average annual growth for powder coatings has been approximately 79% over the last 10 years. 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. Microstructures and phase compositions of coatings obtained by different methods differ significantly. 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. 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. Based on results from several composition iterations, a hfdoped alloy fe28al2cr0.
It is characterized by relatively low costs of its realisation and necessary equipment. Thermal barrier coating on gamma titanium aluminide by ebpvd. Microstructure of aluminide coatings on ti6al4v alloy. High temperature corrosion behavior of iron aluminide alloys. 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. See other formats component part mot ice this paper is a component part of the following compilation report. Aluminide coating single crystal superalloy external zone high temperature oxidation. Aluminide diffusion coatings are proved to be the costeffective solution for high temperature oxidation, which are used widely for protecting turbine blades and vanes. Structural property effects for platinum modified aluminide coatings. Full text of thermodynamics and kinetics of pack aluminide. Nickel aluminide ni 3 al is an intermetallic alloy of nickel and aluminium with properties similar to both a ceramic and a metal. High temperature corrosion type ii 600850c, high temperature corrosion type i 750950c, oxidation 950c and higher.
Aluminide coatings have an ability to form a protective and slowly growing. Diffusion coatings for hightemperature applications on ni. Aluminides are compounds containing aluminum and one or more electropositive elements. Limited mcraly usually ebpvd and some ebpvd tbcs are now in use. The microstructures were characterised by analytical electron microscopy, scanning electron microscopy and xray diffraction. Compatibility of aluminidecoated hastelloy x and inconel 617 in a. Yttrium aluminium garnet yag, y 3 al 5 o 12 is a synthetic crystalline material of the garnet group. The aluminide coating can be formed at lower temperature due to the addition of rare earth oxide in the mixture powders. Metals free fulltext rhodium and hafnium influence on the.
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. Nial, cas number 12003780 see also raney nickel nial 3, cas number 12004716. Corrosion testing of slurry aluminide coatings in molten. A after l200hrs of beat treatment at 00 d calculated after astn hand book. During high activity aluminization a change occurs in the surface platinum composition and structure. Gas turbine component coating systems hitech furnace. 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. Platinumaluminide coatings were applied to polycrystalline, directionally solidified and singlecrystal superalloy rods before they were oxidised in still air at temperatures of and 1100c. Chemical composition was analyzed using eds method. Phase composition of the investigated coatings was made using arl xtra x ray di. Structure of pdzr and ptzr modified aluminide coatings deposited by a cvd method on nickel superalloys article pdf available in kovove materialy 5705. The structure and composition of the coating depends on the substrate, implying that coatings must be tailored for a given alloy. 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. Structure of platinum modified aluminide coatings springerlink.
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. 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. Superalloys source book, american society for metals, 1984. Role of platinum in aluminide coatings sciencedirect. The aluminisation process is performed on steels 244,246,247,269273, superalloys 274281, nonferrous metals 282284, etc. Optimum coating composition in relation to oxidation and hotcorrosion resistance, after m. This technique has been used since the last century 255258, even though its industrial and technical applications are more recent 259, 260. 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 silicon enriched nickel aluminide diffusion coating was ion milled using the focused ion beam fib technique figure 4. The morphology and composition of a coating are functions of the pack. 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. After 1,000 1h cycles, a massive oxide scale was formed with a complex oxide composition and a porous microstructure. The slurry method is one of the oldest techniques of deposition of aluminide coating on the nickel superalloy, titanium alloys and steel.