US3620815A - Vapor collimation in vacuum deposition of coatings - Google Patents
Vapor collimation in vacuum deposition of coatings Download PDFInfo
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- US3620815A US3620815A US806955A US3620815DA US3620815A US 3620815 A US3620815 A US 3620815A US 806955 A US806955 A US 806955A US 3620815D A US3620815D A US 3620815DA US 3620815 A US3620815 A US 3620815A
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- 238000000576 coating method Methods 0.000 title claims abstract description 42
- 238000001771 vacuum deposition Methods 0.000 title claims description 9
- 239000011248 coating agent Substances 0.000 claims abstract description 36
- 238000000034 method Methods 0.000 claims abstract description 35
- 239000011261 inert gas Substances 0.000 claims abstract description 22
- 230000008021 deposition Effects 0.000 claims abstract description 12
- 239000000463 material Substances 0.000 claims description 20
- 239000001307 helium Substances 0.000 claims description 12
- 229910052734 helium Inorganic materials 0.000 claims description 12
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 claims description 12
- 239000000758 substrate Substances 0.000 claims description 11
- 238000000151 deposition Methods 0.000 claims description 10
- 229910045601 alloy Inorganic materials 0.000 claims description 8
- 239000000956 alloy Substances 0.000 claims description 8
- 238000002844 melting Methods 0.000 claims description 4
- 229910052751 metal Inorganic materials 0.000 abstract description 8
- 239000002184 metal Substances 0.000 abstract description 8
- 150000002739 metals Chemical class 0.000 abstract description 4
- 239000011253 protective coating Substances 0.000 abstract description 4
- 239000000155 melt Substances 0.000 abstract description 3
- 229910000601 superalloy Inorganic materials 0.000 abstract description 3
- 239000000203 mixture Substances 0.000 description 8
- 239000007789 gas Substances 0.000 description 7
- 238000012360 testing method Methods 0.000 description 7
- 238000010894 electron beam technology Methods 0.000 description 6
- 238000007740 vapor deposition Methods 0.000 description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 229910002543 FeCrAlY Inorganic materials 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 239000011651 chromium Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 229910052727 yttrium Inorganic materials 0.000 description 2
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 description 2
- 229910000951 Aluminide Inorganic materials 0.000 description 1
- 230000001154 acute effect Effects 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 239000008199 coating composition Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000000280 densification Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000005291 magnetic effect Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 230000004584 weight gain Effects 0.000 description 1
- 235000019786 weight gain Nutrition 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
- C23C14/228—Gas flow assisted PVD deposition
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
- C23C14/24—Vacuum evaporation
Definitions
- the present invention relates in general to metal coating processes and apparatus therefor and, more particularly, to vacuum deposition processes.
- aluminide coatings such as that described in the U.S. Pat. No. 3,102,044, to Joseph have in the past displayed satisfactory performance, it is well known that these coatings, because of their dependence upon the availability of substrate elements, often are characterized by a composition less than optimum. Furthermore, these coatings are often achieved only at the expense of some mechanical property loss in substrate strength.
- CoCrAlY coating at a nominal composition of, by weight, 30 percent chromium, percent aluminum, 0.5 percent yttrium, balance iron, as discussed in the copending application of Frank P. Talboon, Jr., et al. entitled Iron Base Coating for the Superalloys, Ser. No. 731,650 filed May 23, 1968, now U.S. Pat. No. 3,542,530.
- CoCrAlY composition at about, be weight, 21 percent chromium, 15 percent aluminum, 0.7 percent yttrium, balance cobalt,
- a low-velocity, controlled inert gas leak to a chamber pressure sufficiently low to prevent sustaining a gas plasma but sufficiently high to substantially decrease the mean free collision path of the metal vapor atoms in the vicinity of the surface to be coated, has been utilized to randomize the direction of the metal vapor atoms thus permitting the coating of nonline-of-sight areas.
- the present invention contemplates a vacuum deposition process which utilizes controlled inert gas impingement on the vapor cloud to collimate and densify the coating material vapor cloud.
- an inert gas is admitted at high velocity into the vacuum chamber through a gas cascade or multiorificed nozzle surrounding the pool of molten coating material, the gas being introduced at an angle to the vapor cloud to minimize low-angle vapor deposition and, in essence, to pump the vapors into a more concentrated vapor cone.
- FIG. 1 illustrates, somewhat schematically, a vacuum deposition chamber with an inert gas cascade surrounding the molten pool and operating to reduce the angle of the vapor cone.
- FIG. 2 is an expanded view of the molten pool area more clearly showing the relative position of the gas cascade.
- the articles to be coated 2 are mounted within a vacuum chamber 4.
- the parts are usually mounted to effect rotation about their individual axes, typically utilizing a pass-through (not shown) through the vacuum chamber to an external drive system.
- a pass-through not shown
- the parts are normally mounted in a plane of vapor isodensity 6, or roughly along an arc defining a zone of constant vapor concentration, the parts closest to the vertical passing through the center of the molten pool being located slightly farther from the pool surface than those positioned at an angle with respect to said vertical.
- the parts are further positioned as close as possible to the surface of the molten pool for maximum coating efficiency but far enough removed therefrom to prevent coating contamination by splash from the pool.
- the pool height varies with each system but for a 2 inch diameter pool and a deposition rate of about 0.3 mils per minute with a FeCrAlY coating material, a mean height of about 10 inches has been found to be satisfactory.
- a preferred heat source and that illustrated schematically in the drawing is an electron beam gun 8.
- the arrangement of the electron beam gun within the vacuum chamber is a function of design.
- deflection magnetics have been utilized to direct the beam onto the surface 12 of the coating material ingot 10.
- a 30 kilowatt electron beam unit has provided satisfactory deposition rates with a 2 inch diameter ingot, the depth of the molten pool usually being Vatinch.
- the ingot 10 is made movable with respect to the water cooled crucible l4 and is normally continuously fed into the crucible to maintain a constant pool height. This is important for two reasons. First, because the electron beam is focused on the pool surface, it is desirable to maintain the ingot level at the proper height. Secondly, because coating efficiency composition and uniformity are very susceptible to pool height changes, a constant height relationship 16 between pool and parts to be coated is preferred.
- the key to the present invention is theprovision of a multiple orifice inert gas manifold 20 around the periphery of the molten pool, the orifices 21 being angled upwardly and inwardly toward the vapor cloud.
- a high-velocity inert gas stream preferably helium, to reduce the incidence of a plasma gas discharge resulting in process instability, is utilized to narrow the cone configuration of the vapor cloud from its normal wide angle 22 to a more acute angle 24, with a resultant densification of the vapors.
- the inert gas stream reduces the scatter of the vapor cloud and thus reduces the material loss incident to low-angle vapor emission from the melt.
- helium gas was introduced at a line pressure of 17 p.s.i.a. through a 4 inch diameter ring manifold oriented concentric with the 2 inch diameter molten pool.
- the improvement which comprises: establishing a cloud of coating material in vapor form moving between a molten pool of coating material and the articles to be coated, said article to be coated being substantially within the line-of-sight of the molten pool; and at a plurality of locations peripherally of the vapor cloud, injecting a high- TABLE I [Helium collimation oi CoCrAlY vapor cloud] Angle of incidence Distance with reabove spect to Coating Chamber pool pool hori- Article weight time pressure Test Specimen (inches) zontal gain (grams) (min.) (torr) Total 51.8
- tests 2 and 3 were run utilizing the inert gas cascading of the present invention and thus should be compared with tests l and 4 which were run without vapor cloud collimation.
- three specimens were coated simultaneously, specimen 2 being the specimen located directly over the centerline of the 2 inch diameter pool, specimens l and 3 being located closer to the pool but offset from the vertical centerline thereof at an angle of 70 with respect to the pool horizontal.
- a vertical reference specimen located at an angle of 52 with respect to the pool horizontal was utilized to ascertain the effect of vapor cloud collimation on the incidence of lowangle deposition.
- the typical coating procedure has utilized a power setting of the electron beam gun at 21 kilowatts for the CoCrAlY material and at l5.5 kilowatts for the FeCrAlY coating. Control of coating thickness to :0.0005 inch at a designed thickness of 0.005 inch has been consistently achieved.
- chamber pressures should be maintained at a low-enough value to prevent the incidence of a plasma generation in the process which results in a fundamental instability and a loss of control of the process.
- helium rather than argon is preferred for vapor cloud collimation lIlEpOSfiS.
- the very impo factor in the process is the close maintenance of velocity stream of inert gas at an angle toward the vapor cloud to reduce the extent of low-angle vapor deposition and to redirect and collimate the vapors toward the articles to be coated.
- the inert gas is helium.
- the vacuum in the system is sufficiently low to prevent the generation of a plasma in the system as a result of the helium admission.
- the inert gas is helium.
- the pressure in the system is maintained at a value low enough to prevent the generation of a plasma upon the admission of helium to the system.
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physical Vapour Deposition (AREA)
Abstract
In the processes for forming protective coatings on metals, particularly the nickel-base and cobalt-base superalloys, by deposition in vacuum, an inert gas cascade surrounding the melt is utilized to collimate the coating vapor cloud and reduce low angle deposition.
Description
I Unlted States Patent 13,620,815
[72] Inven o s 5 S- lwhel' [50] Field 01 Search 117/106, Newhgton; 107, 107.1; 118/49, 49.1, 50, 48 Mitchell .1. Bela, Huardvllle; DennlsJ. Evans, Rocky Hill; Nicholas E. Ullon, Refel'mm cued Vernon, all 01 Conn. UNITED STATES PATENTS 1 1 p 806,955 2,996,418 8/1961 Bleil 117/106 x 1 Filed 13, 1969 3,373,050 3/1968 Paul 61 al. 117/106 [45] Patented Nov. 16, 1971 [73] Assign United Am Corporation Pnr zary ExamxneryAlfred L. Leavm Em Hartford Com Asszslant Exammer- Kenneth P. Glynn AttorneyRichard N. James [54] VAPOR COLLIMATION 1N VACUUM DEPOSITION 0F COATINGS 6 chum 2 Drawing ABSTRACT: In the processes for forming protective coatings [52] US. 117/106 R, on metals, particularly the nickel-base and cobalt-base su- 117/107, 118/48, 118/49, 117/107.l peralloys, by deposition in vacuum, an inert gas cascade sur- [51] Int. CL. C23c 11/00, rounding the melt is utilized to collimate the coating vapor cloud and reduce low angle deposition.
VAPOR COLLIMATION IN VACUUM DEPOSITION OF COATINGS BACKGROUND OF THE INVENTION The present invention relates in general to metal coating processes and apparatus therefor and, more particularly, to vacuum deposition processes.
It is well-known that the conventional nickel-base and cobalt-base superalloys do not in and of themselves exhibit sufficient oxidation-erosion resistance to provide component operating lives of reasonable duration in the dynamic oxidizing environments such as those associated with the operation of gas turbine engines. Accordingly, it has been the usual practice to provide these alloys with a protective coating in such applications.
Although the aluminide coatings, such as that described in the U.S. Pat. No. 3,102,044, to Joseph have in the past displayed satisfactory performance, it is well known that these coatings, because of their dependence upon the availability of substrate elements, often are characterized by a composition less than optimum. Furthermore, these coatings are often achieved only at the expense of some mechanical property loss in substrate strength.
Many of the more advanced coatings developed for the next generation of jet engines depend in the first instance on the deposition of a high-melting point coating alloy with a concurrent or subsequent reaction with the substrate to attain the desired end composition, microstructure or adherence. These new alloys generally demand the application of special coating techniques to provide the right species in the right amounts at the surfaces to be protected.
Several coating compositions of current interest are described in detail in copending applications of the present assignee. Among these compositions is that hereinafter referred to as the FeCrAlY coating at a nominal composition of, by weight, 30 percent chromium, percent aluminum, 0.5 percent yttrium, balance iron, as discussed in the copending application of Frank P. Talboon, Jr., et al. entitled Iron Base Coating for the Superalloys, Ser. No. 731,650 filed May 23, 1968, now U.S. Pat. No. 3,542,530. Another such composition is the CoCrAlY composition at about, be weight, 21 percent chromium, 15 percent aluminum, 0.7 percent yttrium, balance cobalt,
The basic problems associated with the deposition of these coating alloys relates to their high-melting points and the difficulty of providing the right amount of all of the alloy species in the coating as applied. Satisfactory results have been attained through the use of vacuum vapor deposition techniques, such as that suggested in the U.S. Pat. No. 2,746,420, to Steigerwald. These processes, which have in the past been primarily directed toward the application of relatively low-temperature materials of relatively simple composition, are in the present instance characterized by extreme sensitivity to variations in the process parameters and, accordingly, reproducibility as well as processing expense is a problem.
The vacuum vapor deposition of electron beam melted metals in existing low-evaporation rate, production-type systems, such as high-cyclic speed or strip line coaters, has essentially been limited to line-of-sight coating from the source (molten pool of coating metal) to rotating or linearly moving substrates. Recently, several techniques have been developed to improve the versatility of the basic process through randomization or redirection of the vapor cloud. In one such method, a low-velocity, controlled inert gas leak, to a chamber pressure sufficiently low to prevent sustaining a gas plasma but sufficiently high to substantially decrease the mean free collision path of the metal vapor atoms in the vicinity of the surface to be coated, has been utilized to randomize the direction of the metal vapor atoms thus permitting the coating of nonline-of-sight areas.
SUMMARY OF THE INVENTION The present invention contemplates a vacuum deposition process which utilizes controlled inert gas impingement on the vapor cloud to collimate and densify the coating material vapor cloud. For this purpose, an inert gas is admitted at high velocity into the vacuum chamber through a gas cascade or multiorificed nozzle surrounding the pool of molten coating material, the gas being introduced at an angle to the vapor cloud to minimize low-angle vapor deposition and, in essence, to pump the vapors into a more concentrated vapor cone.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates, somewhat schematically, a vacuum deposition chamber with an inert gas cascade surrounding the molten pool and operating to reduce the angle of the vapor cone.
FIG. 2 is an expanded view of the molten pool area more clearly showing the relative position of the gas cascade.
DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown most clearly in FIG. 1, the articles to be coated 2 are mounted within a vacuum chamber 4. Inasmuch as the process is fundamentally line-of-sight, the parts are usually mounted to effect rotation about their individual axes, typically utilizing a pass-through (not shown) through the vacuum chamber to an external drive system. For minimum nonuniformity of coating between the individual parts, they are normally mounted in a plane of vapor isodensity 6, or roughly along an arc defining a zone of constant vapor concentration, the parts closest to the vertical passing through the center of the molten pool being located slightly farther from the pool surface than those positioned at an angle with respect to said vertical. The parts are further positioned as close as possible to the surface of the molten pool for maximum coating efficiency but far enough removed therefrom to prevent coating contamination by splash from the pool. The pool height varies with each system but for a 2 inch diameter pool and a deposition rate of about 0.3 mils per minute with a FeCrAlY coating material, a mean height of about 10 inches has been found to be satisfactory.
There are a number of heating techniques which have been employed in the past in connection with vacuum deposition and heat treatment. A preferred heat source and that illustrated schematically in the drawing is an electron beam gun 8. The arrangement of the electron beam gun within the vacuum chamber is a function of design. In some installations, deflection magnetics have been utilized to direct the beam onto the surface 12 of the coating material ingot 10. A 30 kilowatt electron beam unit has provided satisfactory deposition rates with a 2 inch diameter ingot, the depth of the molten pool usually being Vatinch.
The ingot 10 is made movable with respect to the water cooled crucible l4 and is normally continuously fed into the crucible to maintain a constant pool height. This is important for two reasons. First, because the electron beam is focused on the pool surface, it is desirable to maintain the ingot level at the proper height. Secondly, because coating efficiency composition and uniformity are very susceptible to pool height changes, a constant height relationship 16 between pool and parts to be coated is preferred.
The key to the present invention is theprovision of a multiple orifice inert gas manifold 20 around the periphery of the molten pool, the orifices 21 being angled upwardly and inwardly toward the vapor cloud. A high-velocity inert gas stream, preferably helium, to reduce the incidence of a plasma gas discharge resulting in process instability, is utilized to narrow the cone configuration of the vapor cloud from its normal wide angle 22 to a more acute angle 24, with a resultant densification of the vapors. In essence, the inert gas stream reduces the scatter of the vapor cloud and thus reduces the material loss incident to low-angle vapor emission from the melt.
lOlOlO O7l2 A number of tests were conducted with various coating materials and various substrate alloys. in one series of tests, helium gas was introduced at a line pressure of 17 p.s.i.a. through a 4 inch diameter ring manifold oriented concentric with the 2 inch diameter molten pool. Fifty-three evenly spaced, 0.036 inch diameter holes 26 through the wall of a stainless steel tube, oriented at an angle of approximately 45 with respect to the vertical, were provided for orificing purposes.
When weight measurements were made (corresponding specimens have been coated with and without the admission of inert gas) increases were noted in those tests utilizing inert gas admission. Additionally, spurious deposits of the coating material in low-angle locations on the vacuum chamber were significantly reduced.
The results of a number of these tests are summarized in the following table.
these conditions as experience has demonstrated the relative criticality of the process to small variations in the process parameters.
While the invention has been described in connection with particular preferred embodiments and examples, these will be understood to be illustrative only. Numerous modifications to the constructional details, materials and process parameters will be evident to those skilled in the art within the true spirit of the invention as set forth in the appended claims.
What is claimed is:
1. in the process for forming protective coatings on metals by vacuum vapor deposition, the improvement which comprises: establishing a cloud of coating material in vapor form moving between a molten pool of coating material and the articles to be coated, said article to be coated being substantially within the line-of-sight of the molten pool; and at a plurality of locations peripherally of the vapor cloud, injecting a high- TABLE I [Helium collimation oi CoCrAlY vapor cloud] Angle of incidence Distance with reabove spect to Coating Chamber pool pool hori- Article weight time pressure Test Specimen (inches) zontal gain (grams) (min.) (torr) Total 51.8
9% 70 18.4 10% 00 19.6 2.5X10" He Total 57.6
9% 70 17.9 10% 00 20.3 28. 2 4-8X10- He Total 57 4 Total 49.3
Vertical rel 0% 52 1.
Referring to table I, it will be noted that tests 2 and 3 were run utilizing the inert gas cascading of the present invention and thus should be compared with tests l and 4 which were run without vapor cloud collimation. In each case, three specimens were coated simultaneously, specimen 2 being the specimen located directly over the centerline of the 2 inch diameter pool, specimens l and 3 being located closer to the pool but offset from the vertical centerline thereof at an angle of 70 with respect to the pool horizontal.
A vertical reference specimen located at an angle of 52 with respect to the pool horizontal was utilized to ascertain the effect of vapor cloud collimation on the incidence of lowangle deposition.
it will be noted that in each case specimen weight gain was increased with inert gas admission through the cascade and low-angle deposition was decreased.
The typical coating procedure has utilized a power setting of the electron beam gun at 21 kilowatts for the CoCrAlY material and at l5.5 kilowatts for the FeCrAlY coating. Control of coating thickness to :0.0005 inch at a designed thickness of 0.005 inch has been consistently achieved.
it has been mentioned previously that chamber pressures should be maintained at a low-enough value to prevent the incidence of a plasma generation in the process which results in a fundamental instability and a loss of control of the process. In the present process to reduce the possibility of plasma generation, helium rather than argon is preferred for vapor cloud collimation lIlEpOSfiS.
The very impo factor in the process, once satisfactory coating conditions are attained, is the close maintenance of velocity stream of inert gas at an angle toward the vapor cloud to reduce the extent of low-angle vapor deposition and to redirect and collimate the vapors toward the articles to be coated.
2. The method according to claim l, wherein:
the inert gas is helium.
3. The method according to claim 2 wherein:
the vacuum in the system is sufficiently low to prevent the generation of a plasma in the system as a result of the helium admission.
4. The method of improving the efficiency of deposition in vacuum coating processes wherein a high-melting point alloy is to be coated upon a metallic substrate which comprises: establishing a moving cloud of coating material vapor between the source of coating material and the substrate to be coated, said article to be coated being substantially within the line of sight of the molten pool; encircling the source of coating material with an inert gas cascade having a plurality of exit parts angularly directed inwardly toward and upwardly from the source; and admitting an inert gas at high-velocity through the exit ports to collimate the coating material vapor toward the vertical line-of-sight between the source and the substrate.
5. The method according to claim 4, wherein:
the inert gas is helium.
6. The method according to claim 5 wherein:
the pressure in the system is maintained at a value low enough to prevent the generation of a plasma upon the admission of helium to the system.
l i i lOlOlO 07l3
Claims (5)
- 2. The method according to claim 1 wherein: the inert gas is helium.
- 3. The method according to claim 2 wherein: the vacuum in the system is sufficiently low to prevent the generation of a plasma in the system as a result of the helium admission.
- 4. The method of improving the efficiency of deposition in vacuum coating processes wherein a high-melting point alloy is to be coated upon a metallic substrate which comprises: establishing a moving cloud of coating material vapor between the source of coating material and the substrate to be coated, said article to be coated being substantially within the line of sight of the molten pool; encircling the source of coating material with an inert gas cascade having a plurality of exit parts angularly directed inwardly toward and upwardly from the source; and admitting an inert gas at high-velocity through the exit ports to collimate the coating material vapor toward the vertical line-of-sight between the source and the substrate.
- 5. The method according to claim 4 wherein: the inert gas is helium.
- 6. The method according to claim 5 wherein: the pressure in the system is maintained at a value low enough to prevent the generation of a plasma upon the admission of helium to the system.
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US80695569A | 1969-03-13 | 1969-03-13 |
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Cited By (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3971661A (en) * | 1972-06-14 | 1976-07-27 | Westinghouse Electric Corporation | Formation of openings in dielectric sheet |
US4006268A (en) * | 1975-03-17 | 1977-02-01 | Airco, Inc. | Vapor collimation in vacuum deposition of coatings |
US4023999A (en) * | 1972-06-14 | 1977-05-17 | Westinghouse Electric Corporation | Formation of openings in dielectric sheet |
US4024294A (en) * | 1973-08-29 | 1977-05-17 | General Electric Company | Protective coatings for superalloys |
US4233342A (en) * | 1978-05-13 | 1980-11-11 | Leybold-Heraeus Gmbh | Method for vapor-coating turbine buckets |
US4321311A (en) * | 1980-01-07 | 1982-03-23 | United Technologies Corporation | Columnar grain ceramic thermal barrier coatings |
US4321310A (en) * | 1980-01-07 | 1982-03-23 | United Technologies Corporation | Columnar grain ceramic thermal barrier coatings on polished substrates |
EP1436441A2 (en) * | 2001-09-10 | 2004-07-14 | University Of Virginia Patent Foundation | Method and apparatus application of metallic alloy coatings |
US20080066834A1 (en) * | 2006-09-18 | 2008-03-20 | Jepson Stewart C | Direct-Fired Furnace Utilizing an Inert Gas to Protect Products Being Thermally Treated in the Furnace |
US20090136884A1 (en) * | 2006-09-18 | 2009-05-28 | Jepson Stewart C | Direct-Fired Furnace Utilizing An Inert Gas To Protect Products Being Thermally Treated In The Furnace |
US10724133B2 (en) | 2016-09-14 | 2020-07-28 | Raytheon Technologies Corporation | EBPVD columnated vapor stream |
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US2996418A (en) * | 1957-06-05 | 1961-08-15 | Gen Motors Corp | Method and apparatus for vapor depositing thin films |
US3373050A (en) * | 1964-12-30 | 1968-03-12 | Sperry Rand Corp | Deflecting particles in vacuum coating process |
-
1969
- 1969-03-13 US US806955A patent/US3620815A/en not_active Expired - Lifetime
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2996418A (en) * | 1957-06-05 | 1961-08-15 | Gen Motors Corp | Method and apparatus for vapor depositing thin films |
US3373050A (en) * | 1964-12-30 | 1968-03-12 | Sperry Rand Corp | Deflecting particles in vacuum coating process |
Cited By (15)
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