WO2007124396A2

WO2007124396A2 - Treating an object having an amount of ceramic material

Info

Publication number: WO2007124396A2
Application number: PCT/US2007/067042
Authority: WO
Inventors: Thomas J. Butler; Daniel G. Alberts
Original assignee: Ormond, Llc
Priority date: 2006-04-21
Filing date: 2007-04-20
Publication date: 2007-11-01
Also published as: WO2007124396A3

Abstract

A cavitation system and a process for treating an object, specifically an object containing an amount of ceramic material, operates to increase a property of at least the ceramic material within the object. The cavitation system includes a high pressure pump or fluidjet, a nozzle, and a hyperbaric chamber that holds the object to be treated. The treatment of the object includes submerging the object in a fluid medium, which may be within a hyperbaric chamber. The fluidjet and the nozzle then generate a large number of cavitation bubbles within the fluid medium. The cavitation bubbles collapse near a surface of the object and release large amounts of energy, which improves or increases a property, such as a mechanical property, of at least the ceramic material in the object.

Description

TREATING AN OBJECT HAVING AN AMOUNT OF CERAMIC MATERIAL

INVENTORS THOMAS J. BUTLER DANIEL G. ALBERTS

PRIORITY CLAIM

[0001] This application claims priority to U.S. Provisional Application No. 60/745,355, filed April 21, 2006 and U.S. Application No. 1 1/737,686 filed April 19, 2007, which applications are hereby incorporated by reference in their entirety as fully set forth herein.

FIELD OF THE INVENTION

[0002] This invention relates generally to the treatment of objects made at least in part of a ceramic material, and more specifically to a treatment process using cavitation or shot peening on the surface of the object to alter an aspect of the ceramic material.

BACKGROUND OF THE INVENTION

[0003J Engineered ceramics, also called advanced or technical ceramics, are used in a variety of applications, but in those applications they currently have a number of limitations. Typical materials for engineered ceramics include silicon nitride, silicon carbide, boron carbide, boron nitride, alumina, aluminum nitride, tungsten carbide, polycrystalline diamond (PCD), sapphire, yttrium oxide, zinc sulfide and low expansion glass such as Schott Zerodur or Corning ULE. Engineered ceramics have been used for bearings in selected applications because of their high wear resistance and rolling contact fatigue resistance, but the load has to be limited or fracture will occur. Ceramics have been used for body armor and armor plating for aircraft and vehicles, but their ability to stop high energy projectiles is subject to the limitations of the ceramic material^'s toughness and load bearing capability. Ceramics are also being considered for helmets. Ceramics are used in high temperature applications, such as in gas turbine hot section blades, but their longevity and ability to tolerate foreign object damage is limited by their fracture toughness and strength. Other applications of ceramics include nose cones, semiconductor fabrication, medical device parts, and space mirrors. [0004] Some of the current limitations of ceramics are low fracture toughness compared to most metals, low tensile and shear strengths so they can^'t be used in applications where these stresses would be high, and poor notch resistance so stress concentrations such as occur at holes, corners, and edges can cause catastrophic failure.

[0005J Conventional shot peening of metals is a cold working process in which small spherical media called shot bombard the surface of a part. As each piece of shot strikes the material it imparts to the surface a small indentation or dimple. To create the dimple, the surface of the material must yield. Below the surface, the material tries to restore its original shape, thereby producing a zone of cold-worked material stressed in compression. The overlapping dimples create a uniform layer of compressive stress. [0006] Fatigue and stress corrosion failures usually originate at the surface of a part, but cracks will not initiate or even propagate in a sufficiently comprcssivcly stressed zone. Compressive stresses are beneficial in increasing resistance to fatigue failures, ductility, corrosion fatigue, stress corrosion cracking, hydrogen assisted cracking, fretting, galling and erosion. In most modes of fracture and eventual failure, the common denominator is tensile stress. Thus, shot peening is one way of considerably increasing an operational life of a component.

[0007] Although shot peening has been long used to induce compressive stresses in metal components, it has generally been understood that shot peening of ceramic materials would not provide any beneficial results or would result in unwanted or non- desirable surface damage. To date, there is only one known application in which a ceramic object is shot peened to achieve some beneficial result. The application involves shot pcening of ceramic bearings (i.e., made from alumina or silicon nitride) to improve a non-impact load bearing capability of the bearing. The shot pcening technique must be closely controlled to provide a low intensity (e.g., low impact or low pressure) peening for minimizing surface cracking and surface roughening. The shot peening process may, if properly controlled, induce a transformed layer over the surface of the part to enhance the bearing^'s load bearing capability. The technique is described in "Shot Peening of Ceramics: Damage or Benefit?^" by WuIf Pfeiffer and Tobias Frcy, Fraunhofer Institute for Mechanics of Materials (October 8, 2001 ).

(0008] Other attempts have been made to make ceramic materials tougher or less brittle. Ceramic materials have been reinforced with fibers to arrest propagating cracks, but reinforcing with fibers is expensive and makes the material difficult to process. It can also compromise the material^" s wear or high temperature resistance.

[0009] Ceramics have been alloyed with other materials to provide transformation toughening so the material changes crystal structure under stress to put the crack tip in compression and thereby stop its propagation. Transformation toughened zirconia (TTZ) is such a material. The cavitation process may be used with this type of material to induce a transformed layer over the surface and thus further enhance a mechanical property of the material. However, alloying is not possible with all ceramics and frequently results in compromising other desirable properties such as hardness and wear resistance. Other attempts to compensate for poor fracture toughness have involved the use of tougher supporting frameworks such as steel support rings or designing the ceramic component to minimize sharp corners and other stress increasing structures. All of these techniques limit the usefulness of the ceramic material in some manner. [0010] There are relatively few surface engineering processes applicable to ceramics. Some of the techniques that are currently used to increase the toughness of ceramics are ion implantation, ion beam mixing, and laser treatments.

(00111 l°ⁿ implantation involves bombarding the ceramic material with ions to introduce a large biaxial compressive residual stress in the surface of a ceramic material. The damage created by the ions as they come to rest in the material (and to a lesser extent the ions themselves) causes an expansion of the layer which puts it into compression and closes surface flaws. In addition, the ion implantation modifies the plasticity of the surface layer and thus reduces the likelihood of crack initiation. [0012] Ion beam mixing improves the toughness of ceramics by evaporating a thin layer of a metal (such as nickel or titanium) onto the ceramic surface and then bombarding the surface with an ion beam (generally of argon or another inert gas) to mix it with the surface layer of the ceramic. This technique results in a much higher metal content in the surface layer without recourse to the expensive metal ion implantation processes described above.

[0013] Laser treatments improve the toughness of ceramics through a laser glazing process where the surface of the ceramic is locally melted and can flow to fill pores or cracks. This process may be used to seal porous materials for use in vacuum equipment as well as improve the toughness of the ceramic. Alternatively the laser may be used to melt a thin metal coating deposited onto the surface of the ceramic such that the melted metal coating penetrates and fills surface flaws and improves the toughness of the ceramic.

[0014] In addition to the aforementioned ceramic treatment options, others have attempted to impart residual stresses into ceramic material via thermal treatments. For example, it has been proposed to build up a ceramic component in layers, with each layer having a different thermal coefficient of expansion (CTE) than the adjacent layer. Thermal processing of the ceramic component fuses the layers together while imparting residual stresses into the ceramic component. [0015] It would be desirable to improve the toughness or other aspects of the ceramic material without degrading other characteristics, without damaging the ceramic material, and in some cases without damaging a surface finish of the ceramic object being treated. SUMMARY OF THE INV ENTION

|0016] A system and processes for treating an object, specifically an object containing an amount of ceramic material includes a cavitation process that operates to increase a mechanical property of at least the ceramic material within the object. A cavitation system for carrying out the cavitation process includes a high-pressure fluidjet cooperating with a fluid medium in a hyperbaric chamber to generate cavitation bubbles on or near a surface of the object.

[00171 A method for treating an object having an amount of ceramic material includes a first step of submerging the object in a fluid medium, which may be within a hyperbaric chamber. The next step involves generating a number of cavitation bubbles within the fluid medium via a cavitation system. The cavitation system may include a high pressure pump or fluidjet, a nozzle, and a hyperbaric chamber containing a fluid medium. A final step involves collapsing the number of bubbles in proximity to a surface of the object. A cumulative effect of the collapsing bubbles improves or increases a mechanical property of at least the ceramic material in the object.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Preferred and alternative embodiments of the present invention are described in detail below with reference to the following drawings. [0019] FIGURE 1 is an isometric view of a cavitation system according to an embodiment of the invention;

[0020] FIGURE 2 is a schematic representation of a cavitation system according to another embodiment of the invention; [0021] FIGURE 3 is an isometric view of a cavitation system according to yet another embodiment of the invention;

[0022] FIGURE 4 is a diagram illustrating a cavitation process for a single cavitation bubble; and [0023] FIGURE 5 is a flowchart showing a cavitation process according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0024] The current invention induces residual compressive stresses in objects made of ceramic materials without adversely compromising other desirable properties based on an intended use of the final product. In an embodiment of the invention, a ceramic object or an object containing some amount of ceramic material is subjected to a surface treatment process that improves a property of the ceramic object, such as improving a load bearing capability, damage tolerance, or other property of the ceramic object. In one example, the surface treatment process is a cavitation process for improving a fracture toughness of the ceramic object by imparting deep residual compressive stresses into the ceramic object.

[0025] A ceramic object may be an object that is made wholly from one or more ceramic materials or may be an object that includes only some amount of ceramic material. Further, a ceramic material may be an inorganic non-metallic material whose formation is due to the action of heat. The American Society for Testing and Materials

(ASTM) defines a ceramic material as "an article having a glazed or unglazed body of crystalline or partly crystalline structure, or of glass, which body is produced from essentially inorganic, non-metallic substances and either is formed from a molten mass which solidifies on cooling, or is formed and simultaneously or subsequently matured by the action of the heat.^"'

[0026] Ceramic materials are usually ionic or covalently-bonded materials, and can be crystalline or amorphous. A material held together by either type of bond will tend to fracture before any significant plastic deformation takes place, which results in poor toughness in these materials. Additionally, because ceramic materials tend to be porous, the pores and other microscopic imperfections act as stress concentrators, decreasing the toughness further, and reducing the tensile strength. These combine to give catastrophic failures, as opposed to the normally much more gradual failure modes of metals. [0027] Ceramics do, however, show some plastic deformation. But, due to the rigid structure of the crystalline materials, there are very few available slip systems for dislocations of molecules in a matrix to move, and so ceramics deform very slowly. With the non-crystalline (glassy) materials, viscous flow is the dominant source of plastic deformation, and is also very slow. It is therefore neglected in many applications of ceramic materials.

[0028] For ductile materials (e.g., most metals) failure is usually associated with the yield strength of the ductile material; whereas for brittle materials (e.g., ceramic materials) failure is usually associated with the fracture strength of the brittle material. Hence, the principal limitation of ceramics is their brittleness, which is their tendency to fail suddenly with little plastic deformation. This is of particular concern when ceramic materials are used in structural applications. In metals, the delocalized electrons allow the atoms to change neighbors without completely breaking the bond structure. This allows the metal to deform under stress. But, in ceramics, due to the combined ionic and covalent bonding mechanism, the particles cannot shift easily. The ceramic breaks when too much force is applied, and the work done in breaking the bonds creates new surfaces upon cracking.

[0029] In one embodiment, a cavitation system and process employs cavitation bubbles to impart compressive stresses to the ceramic object. The cavitation process may advantageously achieve much better results than shot peening or other methods of toughening ceramics because the cavitation process causes the compressive stresses to go much deeper, sometimes up to ten (10) times deeper than other ceramic treatment methods. The deeper the compressive stress generally means that the object will have a greater tolerance for larger flaws and improved material properties, such as an improved fatigue resistance (i.e., a higher fatigue strength) and an improved impact resistance. In comparison to some of the above-described methods for treating ceramic objects, the cavitation process does not remove material from the object, does not require reinforcement or layering of the ceramic material in the object, and does not substantially alter a surface roughness of the object. The lack of surface roughening is particularly valuable for applications involving transparent ceramics, such as glass, sapphire, yttrium oxide and others that are used for infrared windows and vehicle windows.

[0030] The aforementioned processes may be used to improve various properties of ceramic objects, particularly their fracture toughness (i.e., damage tolerance), fatigue strength, impact or ballistic resistance, and load bearing capabilities. It is therefore useful wherever these properties are important. The processes may be used to improve the load bearing capabilities of ceramic and hybrid bearings. In one embodiment, the cavitation process is used to improve the projectile resistance of personal body armor, helmets, and vehicle armor, including aircraft and helicopter armor. Changing the properties of a surface layer can be particularly useful, since this can turn or rotate the incoming projectile, causing it to present a larger surface area and increasing the armor^'s ability to resist penetration. The processes may be used to reduce chipping and edge failure in ceramic sputtering targets and to reduce foreign object damage susceptibility of ceramic engine components, such as turbine blades. Further, the processes may be used to increase a thermal shock resistance for ceramic object that experience rapid thermal cycling and improve wear resistance in ceramic check valve balls and seats. Wear of cutters used in machining and drilling for oil and gas may also be reduced performing the cavitation process on ceramic and ceramic-composite cutting elements.

[0031] The cavitation process involves the cumulative effect of millions of cavitation bubbles per second collapsing on the surface of the ceramic object to produce a desired residual stress profile and may further produce an increase or an improvement in selected mechanical properties of at least the ceramic material within the object. In this discussion, cavitation bubbles may comprise cavities or voids which may or may not contain vapor. By way of example, the cavitation process may produce a desirable residual compressive stress profile in the ceramic object, may increase the flaw tolerance of the ceramic object, may improve the point or contact load bearing capacity of the ceramic object, may increase a rolling fatigue resistance of the ceramic object, may increase or otherwise improve an impact or ballistic resistance of the ceramic object. In addition to improving or increasing the aforementioned properties, the cavitation process may further operate to a decrease a mean or average statistical variation in the ceramic object^'s material strength. This variation, quantified by the Weibull modulus, is important for design engineers who must size ceramic components to account for a lowest probable strength of the ceramic components. The cavitation process described herein may be employed to increase the Weibull modulus of the ceramic components.

[0032] The residual compressive stresses advantageously operate to reduce or eliminate crack formation and subsequent crack propagation in the ceramic object. In addition or contemporaneously therewith, the cavitation process may increase other mechanical aspects or properties of the ceramic object. Thus, in one embodiment, the cavitation process toughens and strengthens the ceramic object by inducing residual compressive stresses that reach much deeper into the ceramic object than the other surface engineering techniques described above.

(0033] In a preferred embodiment of the invention, a system for carrying out the cavitation process includes a high-pressure fluidjet or pump, a nozzle coupled to the high- pressure fluidjet for generating cavitation bubbles, and a hyperbaric chamber in which the ceramic object is placed in a fluid medium and in which the cavitation process occurs. The high-pressure fluidjet cooperates with the fluid medium to generate cavitation bubbles near or on a surface of the ceramic object. In one embodiment, the pressure of the fluidjet is preferably at least about 5,000 pounds per square inch (psi), which is about 35 Megapascals (MPa).

[0034] FIGURE 1 shows a system 100 for carrying out a cavitation process on a ceramic object 102 according to an illustrated embodiment of the invention. The system 100 includes a hyperbaric chamber 104, a high pressure pump or fluidjet system 106, and a fluid medium 108. The high-pressure pump or fluidjet system 106 includes a nozzle 1 10 configured to generate a fluidjet 120 to generate cavitation bubbles in the fluid medium 108 and where the nozzle 1 10 is located such that the cavitation bubbles collapse on or near a surface of the ceramic object 102.

[0035] hi a preferred embodiment, the hyperbaric chamber 104 is configured to achieve and maintain a fluid medium pressure in a range of about 10 - 200 psi with a preferred pressure of approximately 50 psi. The preferred pressure is equivalent to conducting the cavitation process at a depth of about 100 feet below sea level using a standard pressure rate increase of about 0.5 psi per foot below sea level.

[00361 ^{m one} embodiment, the high pressure pump or fluidjet system 106 includes the nozzle 1 10, a hose 1 12, a coupling member 1 14 for connecting the hose 1 12 to a fluid medium pressure source 1 16, and an articulating ami or manipulator 1 18 for moving the nozzle 1 10 relative to the object 102 in the hyperbaric chamber 104. The high pressure pump or fluidjet system 106 may be an ultra-high pressure pump that generates the fluidjet 120. The fluidjet 120 may take a variety of forms, to include but not limited utilizing different types of fluids, for example water, or another type of fluid. In one embodiment, the fluid is selected for the fluidjet based on a density, a surface tension, or both of the fluid. |0037] The nozzle 1 10 may be sized to fit into small spaces or treat difficult to reach regions of the ceramic object 102. In addition, the fluidjet 120 may be generated using a commercially available system having a dynamic pressure of 350 MPa rated for 60,000 psi at one to four gallons per minute (gpm).

10038] Figure 2 shows another system 200 for carrying out a cavitation process on a ceramic object 202 according to the illustrated embodiment. The system 200 includes a hyperbaric chamber 204, a high pressure pump or fluidjet system 206, and a fluid medium 208. The high-pressure pump or fluidjet system 206 includes an exit nozzle 210 configured to generate cavitation bubbles near a surface 212 of the ceramic object 202. In addition, the high pressure fluidjet system 206 includes a manipulator 214 that moves the ceramic object 202 relative to a fluidjet 216. Alternatively, the object 202 may be fixed and the fluidjet moved over the object 202 or the cavitation process may be carried out using a combination of moving the object 202 and the fluidjet relative to one another. [0039] Figure 3 shows yet another system 300 for carrying out a cavitation process on a ceramic object 302 according to the illustrated embodiment. The system 300 includes a hyperbaric chamber 304, a high pressure pump or fluidjet system 306, a fluid medium (not shown in this embodiment), a pressure source 308, a control unit 310 coupled to an input/output (I/O) interface system 312. The fluidjet system 306 includes a multi-axis robotic manipulator 314 configured to geometrically cooperate with the ceramic object 302.

[0040] FIGURE 4 schematically shows various stages of the cavitation process commencing after a cavitation bubble is generated in a fluid medium by a fluidjet system. In particular, Figure 4 shows the cavitation bubble growth and collapse process that occurs on or near a surface of a ceramic object according to one embodiment of the invention. At stage 400, a first cavitation bubble 420 is initially produced by the high- pressure fluidjet in the fluid medium, where the fluid medium may be under pressure in a hyperbaric chamber. Once created, the cavitation bubble 420 is subjected to a negative pressure 422. [0041] At stage 402, the cavitation bubble 420 enlarges until it reaches a maximum bubble size. Immediately thereafter and at stage 404, the cavitation bubble 420 begins to implode or collapse in compression due to the external pressure 426 on the bubble 420 and the low mass of the bubble 420. At stage 406, the cavitation bubble 420 reaches a minimum size just prior to an implosion or collapse of the cavitation bubble 420. At stage 408, the cavitation bubble 420 implodes or collapses and thereby releases a large amount of energy 430. Much of the released energy is in the form of high pressure shock waves. [0042] In sum, as the cavitation bubble collapses, the pressure and temperature of the vapor within will increase. The bubble will eventually collapse to a minute fraction of its original size or disappear completely via a rather violent mechanism, which releases a significant amount of energy in the form of an acoustic shock-wave. At the point of total collapse, the wave generated by the cavitation bubble may be thousands of pounds per square inch.

[0043] FIGURE 5 shows a cavitation process 500 for treating an object having an amount of ceramic material. At step 502, the object is submerged in a fluid medium, such as water. In one embodiment, the fluid medium is located in and pressurized in a hyperbaric chamber as described above. The chamber may surround the robot or just the fluidjct.

[0044] At step 504, a high pressure pump or fluidjet generates cavitation bubbles in the fluid medium on or near a surface of the object. The fluidjet is moved over the surface of the object or, alternatively, the object is moved under the fluidjet. At step 506, the cavitation bubbles collapse on or near the surface of the object to achieve at least some of plastic deformation of the ceramic material. The collapse of the cavitation bubbles produces molecular movement within the ceramic material and in turn increases a mechanical property, which may include but is not limited to imparting a deep residual stress, increasing a fracture toughness, a fatigue strength, a load bearing capacity, an impact resistance, and/or a thermal shock resistance in at least the ceramic material portion of the object.

[0045] During the cavitation process, operating conditions may be controlled to intensify bubble collapse and thus produce maximum compressive stresses without causing material loss or surface roughening. For example, a lower dynamic fluidjet pressure and a lower fluidjet traverse speed may be used separately or in combination to minimize or eliminate surface roughening. In addition, using a lower fluidjet traverse speed may also increase the amount of residual stress in the ceramic material during the cavitation process. The operating conditions will vary slightly for various types of ceramic objects. For instance, the standoff distance of the fluidjet to the object^'s surface may be increased for softer ceramics. The pressure may be increased for higher strength ceramics, and the traverse speed may be increased where lower strength ceramics are treated. [0046] In the development of the cavitation system and process described herein, the inventors have successfully applied the cavitation process to a ceramic object made of silicon nitride. After completing the process, the surface compressive stresses of the ceramic object increased from about 5 KSI to about 71 KSI. In later developments, the residual compressive stresses increases to 90 KSI. Also during development, ceramic objects made from boron carbide and silicon carbide have also been treated using the cavitation process to achieve surface compressive stresses of 73 KSl for the boron carbide 44 KSI for the silicon carbide.

[0047] As another example, the cavitation process may be applied to transparent or translucent objects to toughen the object without adversely effecting the transmission of rays of light through the object. For example, the cavitation system and process may be applied used in applications such as transparent armor for vehicles and aircraft and for infrared windows like the windows used on missiles and aircraft.

[0048] Strengthening ceramic objects other than those mentioned herein should be considered within the scope of the invention as the process should be effective on other, non-ceramic objects. In addition, the ceramic object may be made of mixed materials containing ceramic, such as ceramic matrix composites or cermets, which are mixtures of ceramic particles in a metal matrix.

[0049] While the preferred embodiment of the invention has been illustrated and described, as noted above, many changes can be made without departing from the spirit and scope of the invention. All of the above U.S. patents, patent applications and publications referred to in this specification, as well as U.S. Patent No. 5,778,713 to Butler et al., are incorporated herein by reference. For example, the hyperbaric chamber pressure may vary, or the cavitation process may be conducted under deep water, thus producing the same effect as a hyperbaric chamber, or the shot peening process may be combined with the cavitation process to obtain both deep and surface residual stress profiles in the ceramic object. Accordingly, the scope of the invention is not limited by the disclosure of the preferred embodiment. Instead, the invention should be determined by reference to the claims that follow.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method for treating an object having an amount of ceramic material, the method comprising: submerging the object in a fluid medium; directing a jet of fluid toward the object to generate a plurality of bubbles within the fluid medium in proximity to the surface of the object; and collapsing the plurality of cavitation bubbles at least in proximity to the surface of the object to induce residual compressive stresses at least a portion of the ceramic material of the object.

2. The method of claim 1. wherein collapsing the plurality of cavitation bubbles at least in proximity to the surface of the ceramic material includes increasing a fracture toughness of the ceramic material.

3. The method of claim 1 , wherein collapsing the plurality of cavitation bubbles at least in proximity to the surface of the ceramic material includes increasing a fatigue strength of the ceramic material.

4. The method of claim 1 , wherein collapsing the plurality of cavitation bubbles at least in proximity to the surface of the ceramic material includes increasing a load bearing capacity of the ceramic material.

5. The method of claim 1 , wherein collapsing the plurality of cavitation bubbles at least in proximity to the surface of the ceramic material includes increasing an impact resistance of the ceramic material.

6. The method of claim 1 , wherein collapsing the plurality of cavitation bubbles at least in proximity to the surface of the ceramic material includes increasing a thermal shock resistance of the ceramic material.

7. The method of claim 1, wherein collapsing the plurality of cavitation bubbles at least in proximity to the surface of the ceramic material includes imparting a residual stress in the ceramic material.

8. The method of claim 1. wherein submerging the ceramic material in a fluid medium includes submerging the ceramic material in a hyperbaric chamber.

9. The method of claim 1 , wherein directing the jet of fluid toward the ceramic material includes directing a jet of water toward the ceramic material.

10. The method of claim 1 , wherein directing the jet of fluid toward the ceramic material includes directing a jet of fluid having a density greater than density of water.

1 1. The method of claim 1 , wherein collapsing the plurality of cavitation bubbles includes moving a fluidjet and the surface of the ceramic material relative to one another.

12. The method of claim 1 , having a surface tension greater than a surface tension of water.

13. The method of claim 12. wherein moving the fluidjet includes moving a high pressure cavitation fluidjet.

14. A method for treating an object having a ceramic portion, the method comprising: submerging the object in a fluid medium; directing a jet of fluid toward the object to entrain a plurality of cavitation bubbles within the fluid medium in proximity to a surface of the object; collapsing the plurality of cavitation bubbles in proximity to the surface of the object; and inducing residual compressive stresses in the ceramic portion of the object.

15. The method of claim 14, wherein submerging the object in the fluid medium includes submerging the object in a hyperbaric chamber containing water.

16. The method of claim 14, wherein submerging the object includes submerging a ceramic matrix composite object in the fluid medium.

17. The method of claim 14, wherein submerging the object includes submerging a metal matrix component with ceramic particles embedded therein in the fluid medium.

18. The method of claim 14. wherein collapsing the plurality of bubbles in proximity to the surface of the object includes collapsing the plurality of bubbles on the surface of the object.

19. The method of claim 14, wherein inducing residual compressive stresses in the ceramic portion of the object includes plastically deforming the ceramic portion of the object to a depth sufficiently below the surface of the object.

20. The method of claim 14, wherein directing the jet of fluid toward the object includes directing the jet of fluid toward the object with a high pressure fluidjct.

21. An object comprising: an amount of ceramic material comprising at least a portion of the object; and a compressive residual stress profile located within at least a portion of the ceramic material proximate a first surface of the object, wherein the compressive residual stress profile is imparted into the ceramic material by collapsing a plurality of cavitation bubbles sufficiently close to the first surface of the object.

22. The apparatus of claim 21 , wherein collapsing the plurality of cavitation bubbles sufficiently close to the first surface of the object includes collapsing the plurality of cavitation bubbles on the first surface of the object.

3. The apparatus of claim 21 , wherein the object is transparent.

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