U.S. patent application number 10/339273 was filed with the patent office on 2003-05-29 for standards, methods for making, and methods for using the standards in evaluation of oxide removal.
Invention is credited to Dupree, Paul Leonard, Lipkin, Don Mark, Weaver, Scott Andrew.
Application Number | 20030100117 10/339273 |
Document ID | / |
Family ID | 23299042 |
Filed Date | 2003-05-29 |
United States Patent
Application |
20030100117 |
Kind Code |
A1 |
Lipkin, Don Mark ; et
al. |
May 29, 2003 |
Standards, methods for making, and methods for using the standards
in evaluation of oxide removal
Abstract
An article of manufacture forms a tool for determining cleaning
parameters of an oxide removal process. The article comprises a
block of material upon which an oxide can be formed and a simulated
defect structure disposed in the block of material. The article is
capable of determining oxide removal parameters of an oxide removal
process by disposing an oxidized standard in a reactor, conducting
an oxide removal process to remove oxide from the standard, and
evaluating the standard and simulated defect structure for
remaining oxide and other oxide removal parameters.
Inventors: |
Lipkin, Don Mark;
(Niskayuna, NY) ; Dupree, Paul Leonard; (Scotia,
NY) ; Weaver, Scott Andrew; (Ballston Lake,
NY) |
Correspondence
Address: |
GENERAL ELECTRIC COMPANY
GLOBAL RESEARCH CENTER
PATENT DOCKET RM. 4A59
PO BOX 8, BLDG. K-1 ROSS
NISKAYUNA
NY
12309
US
|
Family ID: |
23299042 |
Appl. No.: |
10/339273 |
Filed: |
January 9, 2003 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10339273 |
Jan 9, 2003 |
|
|
|
09332617 |
Jun 14, 1999 |
|
|
|
6537816 |
|
|
|
|
Current U.S.
Class: |
436/6 |
Current CPC
Class: |
Y10T 428/12 20150115;
G01N 33/208 20190101; G01N 17/043 20130101; Y10T 428/12215
20150115; G01N 17/04 20130101; G01N 2203/0664 20130101 |
Class at
Publication: |
436/6 |
International
Class: |
G01N 031/00 |
Claims
We claim:
1. An article of manufacture comprising: a block of material, the
block being made of a material upon which an oxide can form; and a
defect structure disposed in the block of material, wherein an
oxidized article is capable of being used to determine parameters
of an oxide removal process by measuring oxide removal from the
block and defect structure after the oxide removal process.
2. An article according to claim 1, wherein the block of material
comprises a nickel-, cobalt-, or iron-nickel-based superalloys, or
combinations thereof.
3. An article according to claim 1, wherein the block of material
comprises a generally rectangular solid block of material.
4. An article according to claim 3, wherein the defect structure
comprises at least one slot disposed in the block of material.
5. An article according to claim 1, wherein the defect structure
comprises at least one slot that is disposed in faces of the block
of material.
6. An article according to claim 5, wherein the at least one slot
comprising a thickness in a range from about 10 micrometers (.mu.m)
to about 1 millimeter (mm ) and a depth in a range from about 10
micrometers to about 10 millimeters.
7. An article according to claim 6, wherein the at least one slot
comprises slots on a plurality of faces of the block.
8. An article according to claim 1, wherein the standard further
comprises a notch disposed in the block of material.
9. An article according to claim 8, wherein the notch comprises a
"V" notch in the block of material.
10. An article according to claim 1, wherein the slot comprising a
constant thickness in a range from about 10 .mu.m to about 2 mm and
a depth in a range from about 10 micrometers to about 10
millimeters, the "V" notch and the slot being separated by a bridge
of material.
11. A tool for determining oxide removal parameters of an oxide
removal process, the tool comprising: a block of material, the
block being formed of a material upon which an oxide can be formed;
and a defect structure disposed in the block of material, wherein
an oxidized tool is capable of being used to determine parameters
of an oxide removal process by measuring oxide removal from the
block and defect structure after the oxide removal process.
12. A tool according to claim 11, wherein the block of material
comprises a nickel-, cobalt-, or iron-nickel-based superalloys, or
combinations thereof
13. A tool according to claim 11, wherein the block of material
comprises a generally rectangular solid block of material.
14. A tool according to claim 11, wherein the defect structure
comprises at least one defect disposed in the generally rectangular
solid block.
15. A tool according to claim 11, wherein the defect structure
comprises slots that are disposed in opposed faces of the generally
defect solid block of material.
16. A tool according to claim 15, wherein the at least one slot
comprising a constant thickness in a range from about 10
micrometers (.mu.m) to about 1 millimeter (mm) and a depth in a
range from about 10 micrometers to about 10 millimeters.
17. A tool according to claim 16, wherein the at least one slot
comprises opposed slots, each opposed slots comprising a constant
thickness in a range from about 10 micrometers (.mu.m) to about 1
millimeter (mm).
18. A tool according to claim 11, wherein the standard further
comprises a notch in the block of material.
19. An article according to claim 11, wherein the notch comprises a
"V" notch in the block of material.
20. A tool according to claim 19, wherein the "V" notch and the at
least one slot are separated by a bridge of material.
21. A tool according to claim 11, wherein defect structure
comprises an oxide-filled, crack-like defect, and the oxide removal
parameters comprise at least one of: depth of oxide removal in the
crack-like defect and the surfaces of the generally rectangular
solid block of material, braze repair capability, depth of braze
filing, and alloying element depletion at the crack-like defect and
surfaces of the block of material.
22. A tool according to claim 21, wherein the oxide removal process
parameters are determined by an evaluation comprising at least one
of: optical inspection, brazing evaluation, weight loss
measurement, electrical resistivity measurement, and wetability
evaluation.
23. A tool according to claim 11, wherein the tool determine
benchmarks for the oxide removal process.
24. A tool according to claim 23, wherein the benchmarks comprise
at least one of: oxide removal amounts as a function of process
time; oxide removal amounts as a function of reactor temperature;
oxide removal as a function of reactor design and loading
configuration; alloying element depletion of the block of material;
alloying element depletion of the block of material as a function
the oxide removal process; efficiency of the individual reactor;
oxide removal as a function of the process run, and oxide removal
as a function of previous oxide removal processes.
25. A process of determining oxide removal status, the process
comprising: disposing an oxidized standard in a reactor, the
reactor capable of implementing an oxide removal process, the
oxidized standard comprising a block of material, the block being
formed of a material upon which the oxide is formed and a defect
structure disposed in the block of material; conducting an oxide
removal process; and evaluating the standard for at least one of
oxide removal amounts as a function of process time; oxide removal
amounts as a function of reactor temperature; oxide removal as a
function of reactor design and loading configuration; alloying
element depletion of the block of material; alloying element
depletion of the block of material as a function the oxide removal
process; efficiency of the individual reactor; oxide removal as a
function of the process run, and oxide removal as a function of
previous oxide removal processes.
26. A process according to claim 25, wherein the slot structure
comprises a simulated crack-like defect and the step of evaluating
comprises exposing the simulated crack-like defect.
27. A process according to claim 26, wherein the standard comprises
the simulated crack-like defect and a notch opposed to the
simulated crack-like defect, the step of exposing the simulated
crack-like defect comprises: compressing the standard at the notch
to expose surfaces of the simulated crack-like defect.
28. A process according to claim 25, wherein the step of evaluating
comprises: exposing the simulated crack-like defect by
metallographically sectioning the standard and splitting the
standard at a simulated crack-like defect.
29. A process according to claim 25, wherein the step of evaluating
comprises: evaluating by optical inspecting, brazing capability
determination, electrical resistivity measuring, weight loss
measuring, and wetability evaluating.
30. A process according to claim 25, wherein the process of
determining oxide removal status further comprises determining at
least one of: oxide removal amounts as a function of process time;
oxide removal amounts as a function of reactor temperature; oxide
removal as a function of reactor design and loading configuration;
alloying element depletion of the block of material; alloying
element depletion of the block of material as a function the oxide
removal process; efficiency of the individual reactor; oxide
removal as a function of the process run, and oxide removal as a
function of previous oxide removal processes.
31. A process for forming an oxide removal process evaluation
standard, the standard comprising a block of material, the block
being formed of a material upon which an oxide can be formed; and a
simulated defect structure disposed in the block of material,
wherein the standard is capable of determining oxide removal
process status, the process comprising: machining the simulated
defect structure in the block of material; and exposing the block
of material to a thermal treatment to form an oxide on the block of
material and on surfaces of the simulated defect structure.
32. A process according to claim 31, wherein the step of exposing
the block of material to a thermal treatment comprises controllably
exposing the block of material to a high-temperature, oxidizing
thermal environment for time period to form oxides on the block and
filling the simulated defect structure.
33. A process according to claim 31, further comprising compressing
the simulated defect structure to form a simulated crack-like
defect after the step of machining the simulated defect structure.
Description
BACKGROUND OF THE INVENTION
[0001] The invention relates to standards for evaluating oxide
removal, methods of making the standards, and their associated
methods of use.
[0002] Aeronautical, marine, and land-based turbine components,
such as, but not limited to, blades, shrouds, and vanes, are
exposed to high-temperature oxidizing, and often corrosive,
environments during service. Surfaces of turbine components,
including cracks, may form complex, chemically stable thermal
oxides during use. These oxides comprise, but are not limited to,
oxides of aluminum, titanium, chromium, and combinations
thereof.
[0003] Turbine components are periodically overhauled in order to
prolong life or enhance performance. During these overhauls, the
turbine components may be subjected to various repair operations,
including welding, brazing, or coating. The presence of stable
oxides impairs the reparability of a superalloy. Therefore, removal
of these oxides prior to repair, for example by cleaning the
turbine components, is important for successful turbine
overhaul.
[0004] Grit-blasting or grinding operations can effectively remove
surface oxides when only superficial repairs are required and the
surfaces to be cleaned are readily accessible. These cleaning
operations, however, are not only labor intensive but can result in
inadvertent and undesirable loss of the base alloy material, thus
compromising the turbine component's reliability and efficiency.
Further, repair of hard-to-reach surfaces, including internal
passages and highly concave sections, such as, but not limited to,
cooling holes, cracks, and slots, generally requires a
non-mechanical cleaning process that minimally degrades or consumes
the base alloy. These cleaning processes have included batch
thermo-chemical cleaning, such as processes that occur in a
high-temperature reactive environment. These batch
turbine-component cleaning processes can, in some cases, rely on
fluoride ions, which are provided in a reactor to remove highly
stable oxides from, cooling holes, cracks, slots, and other
hard-to-reach surfaces. The fluoride-ion cleaning (FIC) processes
are known to remove oxides while leaving the turbine component's
base alloy essentially intact.
[0005] While processes such as FIC are useful for cleaning oxides
on turbine components, the process effectiveness, especially with
respect to oxide removal from, cooling holes, cracks, slots, and
other hard-to-reach surfaces, is difficult to quantify. Known
measures of oxide removal comprise sectioning of cleaned turbine
components and measuring the extent of oxide cleaning. This measure
does not provide a consistent indication of overall oxide removal,
since both the damage and oxidation characteristics of each turbine
component will vary. Therefore, a tool that can consistently gauge
the effectiveness of an oxide removal process would be
desirable.
SUMMARY OF THE INVENTION
[0006] The invention sets forth an article of manufacture
comprising a block of material upon which an oxide can be formed
and a defect structure disposed in the block of material. The
article is capable of being used to assess the effectiveness of an
oxide removal process by measuring oxide removal from the block and
defect structure after subjecting it to an oxide removal
process.
[0007] The invention further sets forth a tool for determining
oxide removal parameters of an oxide removal process. The tool
comprises a block of material upon which an oxide can be formed and
a defect structure disposed in the block of material. The tool is
capable of being used to assess the effectiveness of an oxide
removal process by measuring oxide removal from the block and
defect structure after subjecting it to an oxide removal
process.
[0008] Another embodiment of the invention provides a process for
determining an oxide removal effectiveness. The process comprises
disposing an oxidized standard in a reactor that is capable of
oxide removal. The standard comprises a block of material upon
which an oxide can be formed and a defect structure disposed in the
block of material. The method further includes conducting an oxide
cleaning and evaluating the standard for remaining oxide.
[0009] A further embodiment of the invention comprises a process
for forming an oxide removal evaluation standard. The standard
comprises a block of material upon which an oxide can be formed and
a defect structure disposed in the block of material. The process
comprises machining the slot structure in the block of material,
compressing the defect structure to form at least one crack-like
defect, and exposing the block of material to a thermal treatment
to form an oxide on the block surfaces and within the at least one
crack-like defect.
[0010] These and other aspects, advantages and salient features of
the invention will become apparent from the following detailed
description, which, when taken in conjunction with the annexed
drawings, where like parts are designated by like reference
characters throughout the drawings, disclose embodiments of the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a schematic illustration of a standard for
evaluating effectiveness of oxide removal processes;
[0012] FIG. 2 is a flow chart of a method for making and using
standards, as embodied by the invention, and for evaluating
effectiveness of oxide removal processes; and
[0013] FIG. 3 is a schematic illustration of a second standard for
evaluating effectiveness of oxide removal processes.
DETAILED DESCRIPTION OF THE INVENTION
[0014] Oxide removal from engine-run turbine components is an
important step in turbine component repair and overhaul processes.
The invention provides a tool for evaluating performance of oxide
removal processes. The tool is useful in quantifying oxide removal
from cracks and other hard-to-reach surfaces, including cooling
holes, slots, internal passages, and other highly concave sections
(hereinafter referred to as "defects").
[0015] The tool, as embodied by the invention, comprises a standard
specimen that enables the extent and effectiveness of oxide removal
to be evaluated. The standard comprises a solid article, for
example an article having a generally rectangular-solid geometry.
The standard typically comprises a material similar to that which
is to be cleaned. For example, and in no way limiting of the
invention, if an oxide removal process is used in repair of turbine
components that are formed of superalloy materials, the standard is
formed from a similar superalloy material, such as nickel-,
cobalt-, or iron-based superalloys, or combinations thereof.
[0016] One embodiment of a standard 1 will be described, along with
methods of its formation and use, with reference to FIGS. 1 and 2
and the flowchart of FIG. 3. The following structure is merely
exemplary of standards within the scope of the invention, and is
not meant to limit the invention in any way. The standard 1
comprises a solid block 2 (hereinafter "block"), for example a
block formed of a superalloy material. The scope of the invention
includes forming the block 2 in any appropriate shape, including
but not limited to, a general rectangular solid. The block 2 may
also comprise protrusions and depressions formed thereon. The
following description of the invention will refer to a generally
rectangular block, however this is merely exemplary and is not
meant to limit the invention in any way.
[0017] The block 2 includes a defect structure. The defect
structure comprises at least one slot 3 on surface 4 and the block
2 comprises a notch 5. As illustrated in FIG. 1, the notch 5
comprises a "V" ("Chevron") notch 5 on an opposite surface 6, and
having its apex 13 substantially co-linear with the slot 3. This
configuration of a notch 5 is merely exemplary of notches within
the scope of the invention. The scope of the invention comprises
notches of varying sizes, shapes, and configurations, for example
and in no way limiting of the invention, rectangular, curved, and
combinations thereof.
[0018] The slot 3 comprises a thickness "t", for example a constant
thickness "t" in a range from about 10 micrometers (elm) to about 1
millimeter (mm), and a length in a range from about 1 mm to about
10 mm. The slot 3 and "V" notch 5 are formed in the block 2 by an
appropriate process, such as, but not limited to, a wire
electro-discharge machining (WEDM) process, in step S1 (FIG.
3).
[0019] The depth of the "V" notch 5 is generally similar to the
depth of the slot 3. The "V" notch 5 and slot 3 define a bridge 7
of solid material in the block 2 that is disposed between the slot
3 and "V" notch 5. Typically, the height H, width W, thickness T of
the standard are in a range from about 0.5 centimeter to about 10.0
centimeters. For example, the ratio H/T is in a range from about
0.5 to about 2.0, and the ratio of W/H is in a range from about 0.5
to about 1.0.
[0020] After the "V" notch 5 and the slot 3 are formed in the
standard 1, the block 2 is cleaned in step S2 to remove any residue
from the slot-structure formation processes. For example, if a
machining process is used to form the slot structure, the block is
cleaned to remove residue, such as but not limited to, oils,
machining chips, recast and oxide deposits, and the like.
[0021] If the slot 3 is formed with a thickness t that simulates a
relevant defect thickness, no compression is needed. If the
thickness "t" of the slot 3 is greater than the thickness desired
for use as a standard, the slot 3 can be compressed to a more
desired final thickness. The block 2 is compressed (step S3) by
applying a distributed force on surfaces 18 and 19 in a direction
indicated by arrows 10 (FIG. 1). The formation of a slot structure,
including any compression of the slot(s) creates a structure that
simulates a defect, where defect includes cracks, holes, crevices,
and other hard-to-reach surfaces (hereinafter "simulated
defect").
[0022] After the optional compression, the block 2 is exposed to a
thermal treatment in step S4. An exemplary thermal treatment, which
is within the scope of the invention, comprises, but is not limited
to, a solution heat treatment followed by controlled exposure to a
high-temperature, oxidizing environment for a time period
sufficient to form oxides on both the block surface and the inside
of the simulated defect.
[0023] The standard 1, with the oxide-filled simulated defect can
be used for oxide-removal process evaluation. The evaluation
comprises disposing the oxidized standard 1 in a cleaning reactor.
The scope of the invention comprises any cleaning reactor and any
oxide removal process that the reactor can employ. The exact type
of cleaning reactor and process used does not affect the standard
per se. The standard 1 is placed, by itself, and alternatively with
other standards, in a reactor. Alternatively, the standard 1 is
placed in the reactor with turbine components to be cleaned. The
standard 1 is then subjected to an oxide removal process, in step
S5. Once the oxide removal process is complete, the standard 1 is
removed from the reactor for evaluation.
[0024] The evaluation of the standard 1 comprises exposing the
simulated defect and its surfaces in step S6. The simulated defect
is exposed by compressing the standard 1 at the "V" notch 5, in the
direction of arrows 11 (FIG. 1), thus splitting the standard 1 to
open the simulated defect.
[0025] Evaluation of the simulated defect, in step S7, can also
include metallographically sectioning the standard 1. The surfaces
of the exposed slot 3 are evaluated for extent of oxide removal
using various, known evaluation techniques. These evaluation
techniques, include, but are not limited to, optical inspection,
electrical resistivity measurement, weight loss measurement, and
wetability evaluation.
[0026] A second embodiment of a standard 20, as embodied by the
invention, is illustrated in FIGS. 4 and 5, and its formation and
use are similar to that described above with respect to FIG. 3. The
standard 20 comprises a block 2 of solid material. The simulated
defect for the standard 20 comprises at least one slot 21, which is
formed similar to slot 3 described above. For example, the slot
structure comprises multiple slots 21, which are machined into the
block 2, for example at least one slot in each of surfaces 24 and
26. The following description discusses multiple slots 21, however
this is merely exemplary of the invention and is not meant to limit
the invention in any way.
[0027] The standard 20 is cleaned (step S2) and, if desired,
compressed (step S3) as described above to form simulated defects.
The standard 20 is then subjected to a heat treatment to oxidize
the surface and slot structure. The standard 20 is then oxidized
(step S4), as discussed above. The standard 20 is then disposed in
a cleaning reactor, and subjected to an oxide removal operation
(step S5).
[0028] Once the oxide removal operation is complete, the standard,
which comprises the simulated defect slot structure, is ready for
evaluation. The evaluation comprises exposing the crack-like
defect, such as by metallographic sectioning, in step S6 and
evaluating in step S7.
[0029] The standards 1 and 20 are evaluated for oxide removal,
based on the known starting defect. The evaluation of oxide removal
provides an indication of the effectiveness of the oxide removal
capabilities of the oxide removal process. For example, and in no
way limiting of the invention, performing an oxide removal process
for a prescribed time on a standard having known oxide amount and
in a reactor with known operational specifications provides oxide
removal process benchmarks, which are indicative of the oxide
removal process performance.
[0030] The standard can be used as an oxide-removal process guage
to determine oxide removal process progress. The standard indicates
the degree of oxide removal. For use as an oxide-removal process
gauge, a standard is prepared with known oxide amounts. The
standard is placed in a reactor and cleaned, as discussed above.
The standard, which is disposed in the reactor, can be checked for
the degree of oxide removal against the oxide removal process
benchmarks. Therefore, it is possible to gauge whether a oxide
removal process has removed sufficient oxide amounts for turbine
components.
[0031] Either of the standard structures described above can be
used to evaluate braze or welding repair effectiveness. In a
braze-repair effectiveness evaluation process, a simulated defect
structure is provided in a standard, the standard is oxidized, and
then cleaned, as described above in steps S1 through S5. A braze
alloy is disposed on at least some portion of the standard and may
be placed over at least one of the simulated defect structures. The
standard then undergoes brazing and, if necessary, any subsequent
thermal treatments, as known in the art, to form a brazed standard.
The brazed standard is evaluated, as discussed above in step S7.
For example, the brazed standard is metallographically sectioned,
inspected, and evaluated for braze-repair parameters. Exemplary
braze repair parameters comprise, but are not limited to, extent of
oxide removal, depth of braze filling, and alloying element
depletion. The evaluation of the brazed standard provides an
indication of the effectiveness of the brazing preparation steps
and the effectiveness of the braze repair process.
[0032] As discussed above, the standard's simulated defect
structure configuration may vary. While the above description sets
forth an elongated and planar slot, this slot configuration is
merely exemplary of slot configurations within the scope of the
invention. For example, the scope of the invention comprises a
simulated defect that simulates cooling hole dimensions, which is
used to determine oxide removal from cooling holes in a turbine
component.
[0033] The standards, as embodied by the invention, are also useful
as tools for determining desirable operational bounds for
oxide-removal processes. As known in the art, oxide removal depends
on various factors, including but not limited to, oxide-removal
process temperature, process atmosphere, and process time. As an
exemplary use as a process improvement tool, standards are formed
of the same base material with similarly structured slots as a
turbine component of interest. The nature and extent of oxidation
is essentially identical between the standards. A standard is
subjected to an oxide cleaning run under a first set of process
conditions. A second run using a second standard is made varying at
least one process condition. Subsequent runs using other standards
vary other process conditions. Oxide removal amounts and other
parameters for each of the runs are determined. An enhanced
combination of oxide-removal process conditions, for example an
enhanced oxide-removal amount.
[0034] An exemplary method of forming a standard will now be
discussed. This method is merely exemplary and not meant to limit
the invention in any way. A first step in the preparation of a
standard involves using a wire electro-discharge machine (WEDM) to
form slots in the standard. The structure and operation of standard
WEDMs are known by those of ordinary skill in the art, and thus a
detailed description is not provided. The standard is then etched
and degreased to remove a recast layer therefrom.
[0035] The standard is then compressed, if needed. The compression
occurs in a press that comprises tungsten carbide platens. The
standard is oriented in the press to apply a force in the direction
of arrows 10 (FIGS. 1 and 4). The standard is compressed with a
suitable force to form crack-like defects. When the applied force
is removed, and the slot reopens slightly due to elastic unloading
of the material. The standard's slots are now reduced in thickness
t to less that about 50% of the original thickness. For example, if
0.10 mm wire is used to make a simulated defect in the form of a
slot having a thickness of about 0.12 mm, the simulated defect slot
defect may be compressed to less than about 0.05 mm.
[0036] The solution heat treatment of the standard comprises
placing the standards on an alumina tray, so the slot structures
are out of contact with the tray and adjacent standards do not
touch. The tray is then placed into an air furnace. The temperature
in the furnace is increased to about 1250.degree. C. at a rate of
about 25.degree. C./min and held for about 1 hour to solution the
material. The standards are next oxidized at a temperature of about
1150.degree. C. for about 300 hours. Thereafter, the furnace is
cooled to a temperature below about 100.degree. C. at a rate
sufficient to form dense oxides in the simulated defects.
[0037] While various embodiments are described herein, it will be
appreciated from the specification that various combinations of
elements, variations or improvements therein may be made by those
skilled in the art, and are within the scope of the invention.
* * * * *