Platinum aluminide ptal is the coating choice for many aviation gas turbine hot section airfoils. 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. In this study, the effect of cyclic oxidation, platinum layer thickness and aluminizing process on behavior of ptaluminide ptal coating on nickelbased superalloy rene80 have been investigated. Oct 20, 2009 the platinum aluminide coating comprises platinum and chromium, wherein the chromium is coelectrodeposited with the platinum, wherein the chromium forms a solid solution within the platinum, and the coating is free from, or substantially free from, chlorine, sulfur, phosphorus, or compounds thereof. Role of platinum in aluminide coatings sciencedirect. Cmsx4 ni based superalloy, a platinum modified diffusional aluminide coating, and yttrium stabilized zirconia ysz deposited by ebpvd as the tbc. Oxidation behaviour of palladium modified aluminide. Aluminide and platinum modified coatings were deposited on gtd 111 material using an outward diffusion process. A preliminary investigation of platinum modified aluminide coatings from two commercial sources indicates that oxidation penetration during exposure at 108c. Us5788823a platinum modified aluminide diffusion coating. Is the coating itself cracked or is the base material cracked. May 15, 2007 oxidation resistant nickel aluminide coatings are designed to develop a protective alumina scale during high temperature exposure. Pdf oxidation behavior of hfmodified platinum aluminide. Improved pt aluminide coatings using cvd and novel platinum.
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 structure and composition of these coatings strongly depends on substrate compositions. Platinum aluminide coating structural effects on hot. In this study, the effect of platinum aluminide coating parameters on surface roughness of nickelbased superalloy rene80 was evaluated. Zirconium, hafnium or platinum modification of nial phase increases the oxidation resistance of diffusion aluminide coatings. Ii, wileyvch, london, in materials science and technology series. It is the objective of this study to compare the performance of a thermal barrier coating system utilizing a platinumaluminide bond coat deposited on commercial grades of. This work presents the degradation mechanism of the platinum modified aluminide diffusion coating of the gtd 111 sc nibase superalloy turbine blades after 16000 h of exposition at different thermal cycles critical heating temperatures reported c and 1120c. Virtually any material that can alloy with aluminum can be coated with this procedure. Pdf failure modes of a platinum aluminide environmental coating. It is also referred to as bc in the text because it can be applied either independently as a protective coating or as bc in a tbc coating system. Studies have shown that platinum modified aluminide coatings can exhibit a range of structural variations depending on initial platinum thickness.
Aluminide and platinum modified aluminide coatings have proven to be effective and. Failure modes of a platinum aluminide environmental coating. Platinum aluminide coatings of the present invention may also function as a bond coating for deposition of an additional layer, such as a ceramic thermal barrier coating, directly on the bond coating. Studies have shown that platinum modified aluminide coatings can exhibit a range of structural variations depending on initial platinum thickness, prealuminizing heat treatment, aluminizing cycle, and postcoating heat treatment. Structural property effects for platinum modified aluminide coatings.
The microstructures were characterised by analytical electron microscopy, scanning electron microscopy and x. On oxidation behaviour of platinum aluminide coated nickel. A relatively thick platinum layer l0 pm produced a coating with an outer pt2a layer above other narrow layers. Platinum in aluminide diffusion coatings johnson matthey.
Aug 19, 1997 the present invention provides a method of improving the oxidation resistance of a platinum modified aluminide coating on a nickel base superalloy substrate wherein the platinum modified aluminide coating is produced under cvd conditions effective to from an outwardly grown, single phase coating and concurrently reduce the concentration of one. Platinum accelerates formation of thermal stable oxide al2o3 and improves the oxide scale adherence 12. An investigation of the hot corrosion protectivity. Dec 23, 2014 a second significant source of impurities in platinum modified aluminide diffusion coatings is electroplating, that is, plating bath components s, p, ci, k, ca etc. The evolution of the surface roughness of an initially flat platinummodified nickel aluminide niptal coating on a single crystal superalloy with cyclic oxidation has been measured by optical profilometry and correlated with the aluminide microstructure. Platinummodified diffusion aluminide coatings on nickelbase.
Platinum aluminide coatings for oxidation resistance of. An investigation was carried out to determine the thermal stability of a platinum aluminide coating on the directionally solidified alloy mar m 002 and its singlecrystal version alloy, srr 99, at 800, and 1100c. The desired coating microstructure for the platinum aluminide coatings was an outer layer of two phase ptal2 in a bniptai matrix, a middle zone of f3niai and a. Vapor deposition of platinum alloyed nickel aluminide coatings. The structures of the platinumaluminide coatings on nickel base superalloys are described. A preliminary investigation of platinum modified aluminide coatings from two commercial sources indicates that oxidation penetration during exposure at 108 c. It had been speculated earlier that such structural variation could account at least in part for some of the reported variation of performance of these coatings. Conventional aluminide coatings are widely used for this purpose but platinum aluminides offer improved corrosion resistance. Platinum aluminide coating structural effects on hot corrosion. Conclusions platinum in aluminide coa tings 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 coatings, platinum modi ed nickel aluminide coatings produced by indiusion of 1 in. The coating morphology and chemistry are highly dependent upon the thickness of the platinum layer, pack activity and time of processing.
On the initiation of cyclic oxidationinduced rumpling of. The grain boundaries in thebphase portion are delineated by. Application processes brushed, dipped, flowed or sprayed slurries. Thermal stability of a platinum aluminide coating on nickel. Pdf diffusion behaviour of pt in platinum aluminide. The aluminide coating produced has been characterized in detail elsewhere6. The paper presents comparison of structures of hafnium modified aluminide coatings deposited in two different ways on pure nickel.
In this study, the effect of cyclic oxidation, platinum layer thickness and aluminizing process on behavior of pt aluminide ptal coating on nickelbased superalloy rene80 have been investigated. Us5658614a us08330,694 us33069494a us5658614a us 5658614 a us5658614 a us 5658614a us 33069494 a us33069494 a us 33069494a us 5658614 a us5658614 a us 5658614a authority us united states prior art keywords coating substrate platinum aluminide method prior art date 19941028 legal status the legal status is an assumption and is not a legal conclusion. Ni, ptal phase, and no ptal2 phase was detected, which. 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. Coating system description typical composition typical thickness aluminide provides oxidation protection for nickel, 2230 wt. The system used consisted of a substrate of cmsx4 ni based superalloy, a platinum modified diffusional aluminide coating, and yttrium stabilized zirconia ysz deposited by ebpvd as the tbc. The effects of platinum modification on the isothermal oxidation performance of a chemical vapour deposition aluminide coating are examined.
Surface finishes applied prior to tbc deposition include 120 and 40 minute media finishes, barrel finish, and 3 m hand polish. Alternative to pack and vaporphase aluminizing processes. Pdf diffusion behaviour of pt in platinum aluminide coatings. We have found that a silicon diffused aluminide coating works well for the application and is less expensive than the platinum. Platinum was electrodeposited to varying thicknesses to a maximum of 16. The oxidation and hot corrosion resistance of high temperature nickelbase superalloy com ponents can be improved by aluminide coating. The formation of platinum aluminide coatings on in738 and. The effect of the platinum layer and the aluminizing. The platinum aluminide coatings described here have been developed to protect titanium alloys from oxidation and alpha case formation and can thus. Crosssection of a platinum modi ed nickel aluminide coating after 40 cycles of oxidation to 1150 c revealing the structure of the inner interdiusion zone idz and the outerbphase portion of the coating.
It is well established that platinum additions, typically about 68 at%, provide substantial improvements in oxidation resistance of such coatings, yet the nature of the platinum effect is still not fully understood. The initial coating condition and the evolution of degradation were characterized applying conventional microscopy and. Applied to the component surface and then diffused, these coatings adhere tightly to the part surface. Platinum aluminide coatings johnson matthey technology. A knowledge of the constitution and structure of ptnial coatings developed by diffusion. Although these diffusion methods have successfully synthesized. The specimens have a platinum aluminide coating on a nibased superalloy single crystal cmsx4 substrate. The platinum aluminide coating was produced on imi 834 samples by electrochemically depositing a layer of platinum, 5 p thickness, followed by a diffusion treatment at 700c for two hours under. Surface finishes applied prior to tbc deposition include 120 and 40 minute media finishes, barrel finish, and 3 mm hand polish. Microstructures and hot corrosion resistance of aluminide. Thermal stability of a platinum aluminide coating on.
The structure and the composition of an aluminide coating varies for di. Improved pt aluminide coatings using cvd and novel. Dec 23, 2014 cyclic oxidation behavior of aluminide, platinum modified aluminide, and mcraly coatings has been investigated at three temperatures. Pack cementation process has been applied for depositing aluminide and platinumaluminide coatings on a nickelbase superalloy in738lc. Coating replacements for mcralys or platinum aluminides without platinum available advanced high performance coatings dimensional restoration via nickel cvd coatings downloads aeromet technologies capabilities list february 2015. Cyclic oxidation behavior of aluminide, platinum modified.
Platinummodified diffusion aluminide coatings on nickel. Evaluation of simple aluminide and platinum modified aluminide. Pedraza et al showed that platinum reduces void formation at the interface of metaloxide. Examination of the platinum effect on the oxidation. Crosssection of a platinummodi ed nickel aluminide coating after 40 cycles of oxidation to 1150 c revealing the structure of the inner interdiusion zone idz and the outerbphase portion of the coating.
These coatings are modified by adding are elements such as platinum. The superior performance of the coating is due to the formation of a protective, adherent and continuous alumina scale on its surface. Recently, it has been found that by modifying these standard aluminide coatings with a thin platinum underlay, significant improvements in high temperature corrosion resistance can be achieved. Jul 01, 2001 the superior performance of the coating is due to the formation of a protective, adherent and continuous alumina scale on its surface. The coatings, platinummodi ed nickelaluminide coatings produced by indiusion of 1 in. The electroplating solution preferably includes an alkali element. The plating is very thick but we have never observed this phenomena before. Oxidation resistant nickelaluminide coatings are designed to develop a protective alumina scale during high temperature exposure. Comparative performance of a thermal barrier coating. A platinumaluminide environmental coating has been subjected to simulated operating thermal cycles normally encountered in landbased gas turbines.
Cyclic oxidation behavior of aluminide, platinum modified aluminide, and mcraly coatings has been investigated at three temperatures. Vapor phase aluminide coatings this type of aluminide coating is also referred to a vpa, abovethepack, and gasphase aluminide. The roughness evolution is dominated by the relative motion of individual grains on thermal cycling, with the larger sized grains moving up. Recently, it has been found that by modifying these standard aluminide coatings with a thin platinum. However, the oxidation behaviour of the coating varies from one alloy substrate to another depending upon its chemical composition and, in. Platinum aluminide coating and method thereof honeywell. A preliminary investigation of platinum modified aluminide coatings from two commercial sources indicates that oxidation penetration during exposure at 108c in air is dependent on the initial coating structure. Royce and johnson matthey has now resulted in the development of a platinum aluminide diffusion coating that offers some advantages over the commercial systems.
Structure of platinum modified aluminide coatings springerlink. Ni, ptal coatings were fabricated on dd5 nibased superalloy and pure ni substrates. A method of improving oxidation resistance of a platinum modified aluminide diffusion coating on a substrate involves electroplating the substrate with a platinum layer from an aqueous hydroxide based electroplating solution and aluminizing the substrate to grow the platinum modified aluminide diffusion coating on said layer. Cocraly coating was applied on gtd111 by electron beam physical vapor deposition ebpvd. Characterization of the microstructural degradation of. Platinumaluminide coatings were applied to polycrystalline, directionally solidified and singlecrystal superalloy rods before they were oxidised in still air at temperatures of and 1100c. Oxidation behaviour of platinum modified aluminide coatings. Platinum aluminide cvd coating method howmet research. The adverse operating environments encountered by marine gas turbine components has necessitated the development of various protective coating systems. Cyclic oxidationinduced cracking of platinummodi ed.
A method of improving the oxidation resistance of a platinum modified aluminide coating formed on a nickel base superalloy substrate, comprises providing a platinum layer on the substrate, heating the substrate in a coating retort to a temperature of at least about c. Hafnium modified aluminide coatings obtained by the cvd. Degradation of the platinum aluminide coating on cmsx4 at 1100 c. Rootcause analysis of discoloration of platinum aluminide. An investigation has been carried out to determine the role of platinum in aluminide coatings on selected nickelbased superalloys. Examination of the platinum effect on the oxidation behavior. Platinum aluminide coatings of the present invention may serve as a standalone protective coating. Jan 24, 2012 is the coating itself cracked or is the base material cracked. Recently the platinum has small white spots appearing in the plate in the last 15 minutes of plating. Although the beneficial effect of platinum has long been established and implemented in various coating systems, the actual mechanism by which pt improves alumina adhesion remains uncertain. Rootcause analysis of discoloration of platinum aluminide coated ds cm 247lc of a high pressure nozzle guidevane of an aeroengine. A second significant source of impurities in platinum modified aluminide diffusion coatings is electroplating, that is, plating bath components s, p, ci, k, ca etc. A platinum aluminide environmental coating has been subjected to simulated operating thermal cycles normally encountered in landbased gas turbines. Aluminide coatings are produced based on intermetallic nial.
T he coating, rt22, is manufactured by chromalloy uk. The morphology, structure and microchemical composition of the coating were characterized using scanning electron microscopy, transmission electron microscopy, energy. At byron products our process working zone is approximately 36 in height and 44 in diameter. A platinum aluminide environmental coating has been subjected to simulate d operating thermal cycles normally enc ountered in land based gas turbine s. Platinum aluminide utilizes a platinum electroplate prior to aluminization for 4055 wt.
The microstructure and oxidation resistance of the coating were studied, with a single pt modified aluminide coating as a reference. Effect of surface conditioning of platinum aluminide bond. The pt concentration decreases towards zero as the diffusion zone is approached. For this purpose, different thicknesses of ptlayer 2, 4. Platinum modified aluminidespresent status asme digital. Pdf cyclic oxidation in air at 900 c of a plain aluminide coating and a platinum aluminide coating, developed by the pack cementation.
The grain boundaries in thebphase portion are delineated by the presence ofc0 phase, appearing bright in the image. It is found that platinum improves the protective nature of the coating by 1 increasing its. Oxidation behaviour of platinum modified aluminide. The coating, rt22, is manufactured by chromalloy uk. Platinum alumnide coatings have been produced by first plating a thin layer of platinum usinq a fused salt platinum plating technique and then pack aluminizing using powder packs containingal, nh4 c1 and al 2 0 3 or ni 2a1 3, nh4 c1 and al 203. The oxidation was undertaken in a mixture of gas with 6 vol. The microstructures were characterised by analytical electron microscopy, scanning electron microscopy and xray diffraction. Platinum aluminide coatings for oxidation resistance of titanium. Various microscopy, spectroscopy and diffraction techniques were used to characterize the microstructure. Cyclic oxidationinduced cracking of platinummodi ed nickel. The chemistry and morphology of these coatings on in738 superalloy both in the ascoated and in the subsequently heat treated condition have been. Diffusion aluminide coatings have been used successfully for many years to enhance the hot corrosion resistance of turbine blades and vanes.
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