Platinum accelerates formation of thermal stable oxide al2o3 and improves the oxide scale adherence 12. Platinummodified diffusion aluminide coatings on nickelbase. The aluminide coating produced has been characterized in detail elsewhere6. Cyclic oxidation behavior of aluminide, platinum modified. Examination of the platinum effect on the oxidation. Studies have shown that platinum modified aluminide coatings can exhibit a range of structural variations depending on initial platinum thickness. 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.
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. The microstructures were characterised by analytical electron microscopy, scanning electron microscopy and x. 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. These coatings are modified by adding are elements such as platinum. Various microscopy, spectroscopy and diffraction techniques were used to characterize the microstructure. The effects of platinum modification on the isothermal oxidation performance of a chemical vapour deposition aluminide coating are examined. Ii, wileyvch, london, in materials science and technology series. The grain boundaries in thebphase portion are delineated by the presence ofc0 phase, appearing bright in the image.
On oxidation behaviour of platinum aluminide coated nickel. At byron products our process working zone is approximately 36 in height and 44 in diameter. 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. The electroplating solution preferably includes an alkali element. Recently, it has been found that by modifying these standard aluminide coatings with a thin platinum. May 15, 2007 oxidation resistant nickel aluminide coatings are designed to develop a protective alumina scale during high temperature exposure. 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. A platinum aluminide environmental coating has been subjected to simulate d operating thermal cycles normally enc ountered in land based gas turbine s. Evaluation of simple aluminide and platinum modified aluminide. Although these diffusion methods have successfully synthesized. The superior performance of the coating is due to the formation of a protective, adherent and continuous alumina scale on its surface. Pdf oxidation behavior of hfmodified platinum aluminide. Applied to the component surface and then diffused, these coatings adhere tightly to the part surface.
Is the coating itself cracked or is the base material cracked. A preliminary investigation of platinum modified aluminide coatings from two commercial sources indicates that oxidation penetration during exposure at 108 c. Surface finishes applied prior to tbc deposition include 120 and 40 minute media finishes, barrel finish, and 3 m hand polish. 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. 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 chemistry and morphology of these coatings on in738 superalloy both in the ascoated and in the subsequently heat treated condition have been. For this purpose, different thicknesses of ptlayer 2, 4. 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. Application processes brushed, dipped, flowed or sprayed slurries.
The grain boundaries in thebphase portion are delineated by. Platinum aluminide coatings for oxidation resistance of. The oxidation and hot corrosion resistance of high temperature nickelbase superalloy com ponents can be improved by aluminide coating. Platinum aluminide coating and method thereof honeywell. Cocraly coating was applied on gtd111 by electron beam physical vapor deposition ebpvd. The formation of platinum aluminide coatings on in738 and. 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. Cyclic oxidationinduced cracking of platinummodi ed nickel. An investigation of the hot corrosion protectivity. The coating morphology and chemistry are highly dependent upon the thickness of the platinum layer, pack activity and time of processing.
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. 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. The structure and composition of these coatings strongly depends on substrate compositions. Platinumaluminide coatings were applied to polycrystalline, directionally solidified and singlecrystal superalloy rods before they were oxidised in still air at temperatures of and 1100c. Pdf failure modes of a platinum aluminide environmental coating. Pedraza et al showed that platinum reduces void formation at the interface of metaloxide. Vapor deposition of platinum alloyed nickel aluminide coatings. The coating, rt22, is manufactured by chromalloy uk. Improved pt aluminide coatings using cvd and novel. Platinummodified diffusion aluminide coatings on nickel. Ni, ptal phase, and no ptal2 phase was detected, which. Zirconium, hafnium or platinum modification of nial phase increases the oxidation resistance of diffusion aluminide coatings. Dec 23, 2014 cyclic oxidation behavior of aluminide, platinum modified aluminide, and mcraly coatings has been investigated at three temperatures. Microstructures and hot corrosion resistance of aluminide.
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. Comparative performance of a thermal barrier 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. Oxidation behaviour of platinum modified aluminide. Rootcause analysis of discoloration of platinum aluminide. The specimens have a platinum aluminide coating on a nibased superalloy single crystal cmsx4 substrate. Platinum aluminide coating structural effects on hot. 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. 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. 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. 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. The oxidation was undertaken in a mixture of gas with 6 vol. Aluminide and platinum modified aluminide coatings have proven to be effective and.
The initial coating condition and the evolution of degradation were characterized applying conventional microscopy and. On the initiation of cyclic oxidationinduced rumpling of. The adverse operating environments encountered by marine gas turbine components has necessitated the development of various protective coating systems. 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. 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 roughness evolution is dominated by the relative motion of individual grains on thermal cycling, with the larger sized grains moving up.
Alternative to pack and vaporphase aluminizing processes. The pt concentration decreases towards zero as the diffusion zone is approached. Thermal stability of a platinum aluminide coating on nickel. Examination of the platinum effect on the oxidation behavior. Conventional aluminide coatings are widely used for this purpose but platinum aluminides offer improved corrosion resistance. Aluminide and platinum modified coatings were deposited on gtd 111 material using an outward diffusion process. Cyclic oxidation behavior of aluminide, platinum modified aluminide, and mcraly coatings has been investigated at three temperatures. Platinum aluminide coatings for oxidation resistance of titanium. Virtually any material that can alloy with aluminum can be coated with this procedure. Platinum aluminide coatings johnson matthey technology. The paper presents comparison of structures of hafnium modified aluminide coatings deposited in two different ways on pure nickel. Royce and johnson matthey has now resulted in the development of a platinum aluminide diffusion coating that offers some advantages over the commercial systems.
Ni, ptal coatings were fabricated on dd5 nibased superalloy and pure ni substrates. Cyclic oxidationinduced cracking of platinummodi ed. Recently the platinum has small white spots appearing in the plate in the last 15 minutes of plating. In this study, the effect of platinum aluminide coating parameters on surface roughness of nickelbased superalloy rene80 was evaluated. 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. 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. Structure of platinum modified aluminide coatings springerlink. 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. Vapor phase aluminide coatings this type of aluminide coating is also referred to a vpa, abovethepack, and gasphase aluminide. Improved pt aluminide coatings using cvd and novel platinum. Hafnium modified aluminide coatings obtained by the cvd. Jan 24, 2012 is the coating itself cracked or is the base material cracked. 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.
It is found that platinum improves the protective nature of the coating by 1 increasing its. Cmsx4 ni based superalloy, a platinum modified diffusional aluminide coating, and yttrium stabilized zirconia ysz deposited by ebpvd as the tbc. We have found that a silicon diffused aluminide coating works well for the application and is less expensive than the platinum. Us5788823a platinum modified aluminide diffusion coating. Platinum aluminide cvd coating method howmet research. The plating is very thick but we have never observed this phenomena before. 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. An investigation has been carried out to determine the role of platinum in aluminide coatings on selected nickelbased superalloys. Pdf diffusion behaviour of pt in platinum aluminide coatings. Pack cementation process has been applied for depositing aluminide and platinumaluminide coatings on a nickelbase superalloy in738lc. 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. Aluminide coatings are produced based on intermetallic nial. 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. Effect of surface conditioning of platinum aluminide bond.
Rootcause analysis of discoloration of platinum aluminide coated ds cm 247lc of a high pressure nozzle guidevane of an aeroengine. 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. 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. Diffusion aluminide coatings have been used successfully for many years to enhance the hot corrosion resistance of turbine blades and vanes. Platinum aluminide coating structural effects on hot corrosion. The microstructure and oxidation resistance of the coating were studied, with a single pt modified aluminide coating as a reference.
A preliminary investigation of platinum modified aluminide coatings from two commercial sources indicates that oxidation penetration during exposure at 108c. The structure and the composition of an aluminide coating varies for di. T he coating, rt22, is manufactured by chromalloy uk. Oxidation resistant nickelaluminide coatings are designed to develop a protective alumina scale during high temperature exposure. Platinum aluminide utilizes a platinum electroplate prior to aluminization for 4055 wt. Degradation of the platinum aluminide coating on cmsx4 at 1100 c. Role of platinum in aluminide coatings sciencedirect. 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.
The coatings, platinummodi ed nickelaluminide coatings produced by indiusion of 1 in. Platinum modified aluminidespresent status asme digital. Oxidation behaviour of platinum modified aluminide coatings. The morphology, structure and microchemical composition of the coating were characterized using scanning electron microscopy, transmission electron microscopy, energy. A platinum aluminide environmental coating has been subjected to simulated operating thermal cycles normally encountered in landbased gas turbines.
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. However, the oxidation behaviour of the coating varies from one alloy substrate to another depending upon its chemical composition and, in. A platinumaluminide environmental coating has been subjected to simulated operating thermal cycles normally encountered in landbased gas turbines. Platinum aluminide ptal is the coating choice for many aviation gas turbine hot section airfoils.
A knowledge of the constitution and structure of ptnial coatings developed by diffusion. An investigation of the hot corrosion protectivity behavior. The platinum aluminide coatings described here have been developed to protect titanium alloys from oxidation and alpha case formation and can thus. 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. Pdf cyclic oxidation in air at 900 c of a plain aluminide coating and a platinum aluminide coating, developed by the pack cementation. Platinum aluminide coatings of the present invention may serve as a standalone protective coating. Failure modes of a platinum aluminide environmental coating. The structures of the platinumaluminide coatings on nickel base superalloys are described. Thermal stability of a platinum aluminide coating on. The results clearly suggest that this platinum aluminide coating is a prospective coating material to protect the titanium alloy components both from oxidation and alpha case formation. The microstructures were characterised by analytical electron microscopy, scanning electron microscopy and xray diffraction. Surface finishes applied prior to tbc deposition include 120 and 40 minute media finishes, barrel finish, and 3 mm hand polish. 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. Characterization of the microstructural degradation of.
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