Pressure release mechanism for capsule and method of use with supercritical fluids

A pressure release mechanism for use with a capsule for processing materials or growing crystals in supercritical fluids is disclosed. The capsule with the pressure release mechanism is scalable up to very large volumes and is cost effective according to a preferred embodiment. In conjunction with suitable high pressure apparatus, the capsule with pressure release mechanism is capable of processing materials at pressures and temperatures of 20-2000 MPa and 25-1500° C., respectively. Of course, there can be other variations, modifications, and alternatives.

FIELD OF INVENTION

The disclosure relates generally to a pressure release mechanism for a capsule to be used in high pressure, high temperature applications. The disclosure relates generally to a pressure release mechanism for a capsule to be used with a high pressure apparatus. More particularly, the disclosure relates to a pressure release mechanism for a capsule used in conjunction with a high-pressure apparatus for processing materials in a supercritical fluid.

BACKGROUND

Supercritical fluids may be used to process a wide variety of materials. Examples of supercritical fluids applications include extractions in supercritical carbon dioxide, the growth of quartz crystals in supercritical water, and the synthesis of a variety of nitrides in supercritical ammonia.

Processes that employ supercritical fluids are commonly performed at high pressure and high temperature within a pressure vessel. Most conventional pressure vessels not only provide a source of mechanical support for the pressure applied to reactant materials and supercritical fluids, but also serve as a container for the supercritical fluid and material being processed. The processing limitations for such pressure vessels are typically limited to a maximum temperature in the range between about 400° C. and 600° C. and a maximum pressure in the range between about 100 megapascals (also referred as “MPa”) and 500 MPa. Conventional pressure vessels, or autoclaves, are commonly equipped with a pressure release mechanism, such as a pressure relief valve or a rupture disk, that automatically releases or vents pressure from inside the pressure vessel if the pressure exceeds a predetermined value. Such pressure release mechanisms increase the safety margin for operation of pressure vessels at high pressures and high temperatures.

Processing material with supercritical fluids often requires a container or capsule that is substantially both chemically inert and impermeable to the solvent and any gases that might be generated by the process. The capsule should also be substantially impermeable to any gases or materials on the outside of the capsule. These capsules are commonly made in the form of cylinders, possessing a wall and two ends disposed opposite each other along the axis of the cylinder. In one approach, the material to be processed, along with a solvent (liquid) that forms a supercritical fluid at elevated temperatures, is introduced into a capsule at low temperature. After the capsule has been sealed and returned to near room temperature, the capsule will possess an elevated internal pressure as dictated by the vapor pressure and temperature of the solvent (liquid) within the capsule. In the case of ammonia at room temperature, the pressure within the capsule is approximately 150 pounds per square inch. This internal pressure can cause deformation, strain, cracks, leaks, and failure of the capsule, particularly for capsules larger than several inches in dimension, and/or when the capsule is fabricated from a soft metal such as silver or gold. Reinforcing members for one or more outer surfaces of the capsule may be provided in order to increase its ability to safely handle moderate internal pressures.

Capsules for use with supercritical fluids in high pressure apparatus are often hermetically sealed, by welding or the like. Consequently, it may not be a possible to incorporate a pressure release value or rupture disk into the capsule or high pressure apparatus, potentially raising questions about safety.

Therefore, there is a need for improved techniques for processing materials in a high pressure apparatus are highly desirable. The present invention fulfills this need, among others.

SUMMARY OF INVENTION

Applicant recognizes that traditional pressure relief mechanisms do not lend themselves to hermetically sealed process capsules contained within support structures. Accordingly, Applicant discloses a pressure relief mechanism which allows the sealed process capsule to manage over-pressures in a controlled way by limiting its rupture to a small, predetermined area. In one embodiment, this rupture area is limited by defining a small opening in the support structure through which the sealed process captures deforms until it ruptures in a controlled manner. In one embodiment, the small opening in the support structure is covered with a burst disk which breaks once the expansion of the sealed capsule reaches a certain point and exceeds the fracture strength of the burst disk.

In one specific embodiment, the disclosure describes a capsule device for use with supercritical fluids comprises a sealed process capsule and a capsule support member in mechanical contact with the sealed process capsule. The sealed process capsule is configured to contain a fluid and the capsule support member comprises an opening that is configured to allow the sealed process capsule to be deformed into and ruptured. In a further embodiment, the capsule device comprises a burst disk positioned within the opening and supported within an edge region and unsupported in a central region. The burst disk is configured to burst, allowing the process capsule to extrude into the opening and rupture, releasing at least a portion of the fluid.

In another specific embodiment, the disclosure provides a method for processing a material in a supercritical fluid. In one embodiment, the method includes loading at least one material into an interior volume of a process capsule and sealing the process capsule. The method includes placing the process capsule and a pressure release mechanism comprising a capsule support member in mechanical contact with the process capsule. The capsule support member comprises an opening configured to allow the process capsule to be extruded into and ruptured, releasing at least a portion of the fluid at a predetermined temperature between about 25 degrees Celsius and about 1200 degrees Celsius and a predetermined pressure between about 20 MPa and about 1000 MPa. The method further comprises processing the at least one material at a temperature between about 25 degrees Celsius and about 1200 degrees Celsius and a pressure for a period between about 10 minutes and about 300 days. In some embodiments, the pressure release mechanism further comprises a burst disk positioned within the opening and supported within an edge region and unsupported in a central region. The burst disk is configured to burst, allowing the process capsule to extrude into the opening and rupture, releasing at least a portion of the fluid.

In another specific embodiment, the disclosure provides a pressure release mechanism for processing materials in supercritical fluids at high pressure and high temperature. The pressure release mechanism comprises a first capsule support member configured to be in mechanical contact with a first side of a sealed process capsule, wherein the first capsule support member comprises an opening configured to allow the sealed process capsule to be extruded into and ruptured. The pressure release mechanism further comprises a second capsule support member configured to be in mechanical contact with a second side of the sealed process capsule.

DETAILED DESCRIPTION

In the following description reference is made to a capsule that is suitable for use in high pressure and high temperature applications, and the capsule may be used for processing supercritical fluids or materials within supercritical fluids. The capsule may be disposed within a high-pressure apparatus for processing materials in a supercritical fluid, e.g., processing or growing gallium nitride in a supercritical fluid. Merely by way of example, the disclosure may be applied to growing crystals of GaN, AlN, InN, InGaN, AlGaN, AlInGaN, and others for manufacture of bulk or patterned substrates. Such bulk or patterned substrates can be used for a variety of applications including optoelectronic devices, lasers, light emitting diodes, solar cells, photodetectors, and integrated circuits, transistor devices, other device structures, photoelectrochemical water splitting and hydrogen generation, and others. In the following description, terms such as “top”, “bottom”, “up”, “upward”, “down”, “downward”, “outward”, “inward”, among others are used and are words convenience and are not to be construed as limiting terms.

The present disclosure provides pressure release designs suitable for use with hermetically-sealed capsules in high pressure and high temperature applications. The designs are capable of processing materials at pressures and temperatures of up to approximately 2000 MPa and 1500° C., respectively. One aspect of the present disclosure provides a capsule suitable for use in high pressure and high temperature applications where the capsule wall is radially reinforced by a capsule sleeve. The radially reinforced capsule wall enables the capsule to be pressurized without substantial yielding, bowing, or failure of the capsule, and without requiring exorbitantly thick and expensive capsule materials. In the following description reference is made to this capsule with a capsule sleeve as a “capsule”, “capsule with a sleeve”, “capsule with a reinforced end”, “capsule with a capsule support sleeve”, “capsule with a capsule sleeve”, “capsule with a support capsule sleeve”, among others, and it should be understood that these are terms of convenience and may be used interchangeably and should not be construed as limiting terms. In another aspect of the present disclosure, a dual capsule design is described in which a process capsule is disposed within a support capsule that provides structural support for the process capsule. In the following description reference is made to this process capsule disposed within a support capsule as a “capsule” or “dual capsule” and it should be understood that these are terms of convenience and should not be construed as limiting terms.

FIG. 1is a schematic100showing a capsule118that includes a reinforced end. In various embodiments, capsule118may be referred to as a process capsule. The capsule comprises at least one wall, a closed end, shown on the bottom inFIG. 1, and a sealed end, shown on top. The closed end may be attached to the capsule wall prior to use by means of a butt weld. The process capsule possesses a closed end110, at least one wall106adjoining the closed end110and extending therefrom, and a sealed end104adjoining the at least one wall and opposite of the closed end. “Closed end”, “wall”, and “sealed end” are terms of convenience and should not be considered to be limiting terms. The closed end110, at least one wall, and the sealed end104define an internal volume114within the process capsule capable of containing at least one material and at least one solvent that becomes a supercritical fluid at a high temperature and high pressure condition (also referred to as “HPHT”). HPHT conditions encompass temperatures greater than about room temperature (about 20° C.) and pressures greater than about 1 atmosphere. In one embodiment, the capsule possesses a cylindrical member or shape. In a specific embodiment, the capsule has at least one fill tube102disposed on a portion of the capsule sealed end104. In a specific embodiment, the fill tube102has an opening operably coupled to the interior volume114of the capsule. Capsule118may also be provided with at least one baffle108within internal volume114, the one or more baffles108serving to create separate regions within the internal volume114. The separate regions are in fluid communication with each other since the one or more baffles108will typically have a cross-sectional area smaller than the area defined by the inner diameter of the capsule, thereby producing a fractional open area of the baffle. In a specific embodiment, baffle108has a fractional open area of between about 0.5% and about 60%, but can also have other percentages. The process capsule wall, capsule end, and baffle materials may comprise copper, copper-based alloy, gold, silver, silver-based alloy, palladium, platinum, platinum-based alloy, iridium, ruthenium, rhodium, osmium, titanium, vanadium, chromium, chromium-based alloy, iron, iron-based alloy, nickel, nickel-based alloy, zirconium, niobium, molybdenum, tantalum, tungsten, rhenium, silica, alumina, combinations of any of the foregoing, and the like.

In one embodiment, the process capsule is substantially chemically inert and impermeable with respect to the at least one material, solvent, and supercritical fluid formed by the solvent disposed within the capsule. In certain embodiments, the capsule is impermeable to at least one of hydrogen, oxygen, and nitrogen. The closed end, at least one wall, and sealable end each have a thickness between about 0.1 mm and about 100 mm according to a specific embodiment. Other thicknesses can also be used depending upon the specific embodiment.

In one embodiment, the sealed end of the process capsule is in mechanical contact with a capsule support member116. Capsule support member116may be bonded to the sealed end of the process capsule and fabricated from a material with a higher modulus and yield strength than that of the material from which the capsule is fabricated. Depending upon the embodiment, the term “bonded” is not intended to be limiting and should be interpreted by ordinary meaning used by one of ordinary skill in the art. In certain embodiments, bonding is achieved by means of a diffusion barrier and a braze layer. The inner portion of the ends may comprise the same material as the capsule wall. The outer portion of the ends comprises a material, the capsule support member116, with a higher modulus and yield strength that that of the inner portion. The capsule support member116may comprise steel, stainless steel, carbon steel, nickel, nickel-based alloy, Inconel, Hastelloy®, Ren{tilde over (e)}® 41, Waspalloy®, Mar-M 247®, Monel®, Stellite®, copper, copper-based alloy, zirconium, niobium, molybdenum, tantalum, tungsten, rhenium, platinum, platinum-based alloy, palladium, iridium, ruthenium, rhodium, osmium, titanium, vanadium, chromium, chromium-based alloy, iron, iron-based alloy, gold, silver, or aluminum, combinations of any of the foregoing, and the like. The thickness of the capsule support member116may be between 0.050 inches and 2 inches. The diameter of the capsule support member116may be equal, to within about 0.050 inches, of the diameter of the remainder of the respective process capsule end. Of course, there can be other variations, modifications, and alternatives. Additional features of the capsule are described in U.S. Patent Publication Number 2009/0301388A1, which is hereby incorporated by reference in its entirety. In various embodiments, the closed end of the process capsule may also be reinforced. In such embodiments, the closed end of the process capsule is mechanical contact with capsule support member120.

Capsule support member116comprises a relief opening122configured such that the process capsule may be deformed into the relief opening and ruptured when a predetermined internal pressure limit of the process capsule is exceeded. At least one of the size, shape and location of the relief opening may be selected to allow the process capsule to rupture when the pressure within the process capsule exceeds the predetermined pressure limit. By varying at least one of the size, shape and location of the relief opening, the internal pressure at which the process capsule ruptures may be controlled. In various embodiments, Capsule100also comprises a burst disk330, described in detail below.

FIG. 2is a diagram200showing a dual capsule220design (which may be referred to simply as a “capsule”) wherein a process capsule214is disposed within a support capsule having a support capsule wall212. The support capsule provides structural support for the process capsule and comprises at least one capsule support member that is mechanical contact with the process capsule. Furthermore, process capsule214may also be provided with at least one baffle108within internal volume114, the one or more baffles108serving to create separate regions within the internal volume114. In one embodiment, the support capsule comprises a support capsule first closed end210, at least one support capsule wall212adjoining the support capsule first closed end210and extending therefrom, and a support capsule second closed end216adjoining the at least one support capsule wall212and opposite of the support capsule first closed end210. “Support capsule first closed end”, “support capsule wall”, and “support capsule second closed end” are terms of convenience and should not be considered limiting terms. In various embodiments, “Support capsule first closed end”, “support capsule wall”, and “support capsule second closed end” may be referred to as capsule support members. The support capsule first closed end210, at least one support capsule wall212, and the support capsule second closed end216define an internal volume capable of receiving and containing a process capsule. The process capsule possesses a process capsule closed end110, at least one process capsule wall106adjoining the process capsule closed end110and extending therefrom, and a process capsule sealed end104adjoining the at least one process capsule wall and opposite of the process capsule closed end110. The process capsule closed end110, at least one process capsule wall106, and the process capsule sealed end104define an internal volume114within the process capsule capable of containing at least one material and at least one solvent that becomes a supercritical fluid at a high temperature and high pressure condition (also referred to as “HPHT”). In certain embodiments, the process capsule is hermetically sealed but the support capsule is not. HPHT conditions encompass temperatures greater than about 100 degrees Celsius and pressures greater than about 1 atmosphere. In some applications the fluid may remain subcritical at HPHT, that is, the pressure or temperature may be less than the critical point. However, in all cases of interest here, the fluid is superheated, that is, the temperature is higher than the boiling point of the fluid at atmospheric pressure. The term “supercritical” will be used throughout to mean “superheated,” regardless of whether the pressure and temperature are greater than the critical point, which may not be known for a particular fluid composition with to dissolved solutes. In one embodiment, the capsule possesses a cylindrical member or shape. Process capsule214may also be provided with at least one baffle108within internal volume114, the one or more baffles108serving to create separate regions within the internal volume114. The separate regions are in fluid communication with each other since the one or more baffles will typically have a cross-sectional area smaller than the area defined by the inner diameter of the capsule, thereby producing a fractional open area of the baffle. In a specific embodiment, baffle108has a fractional open area of between about 0.5% and about 75%, but can also have other percentages. The process capsule wall, process capsule end, and baffle materials may comprise copper, copper-based alloy, gold, silver, silver-based alloy, palladium, platinum, platinum-based alloy, iridium, ruthenium, rhodium, osmium, titanium, vanadium, chromium, chromium-based alloy, iron, iron-based alloy, nickel, nickel-based alloy, zirconium, niobium, molybdenum, tantalum, tungsten, rhenium, silica, alumina, combinations of any of the foregoing, and the like.

In various embodiments, the structural support capsule prevents substantial deformation, strain, cracks, leaks, and/or failure of the process capsule due to the longitudinal and radial stresses that result from heating the process capsule after filling the process capsule with a solvent. The solvent (or fluid) within the process capsule will have a particular pressure as dictated by the specific fluid type and its density and temperature, and this pressure can result in significant stresses on the process capsule, especially for capsules with one or more large dimensions. The present disclosure enables the inner process capsule to be pressurized without significant yielding or bowing of the capsule that potentially results in process capsule failure. Some bowing of the process capsule may occur, but not enough to result in process capsule failure. Instead, according to the disclosure, the process capsule is supported by the support capsule.

The support capsule prevents cracks, leaks, and catastrophic failure of the process capsule for the instances when the process capsule does experience some yielding or bowing. The outer support capsule may comprise steel, stainless steel, carbon steel, nickel, nickel-based alloy, Inconel®, HasteHoy®, Rene® 41, Waspalloy R, Mar-M 247®, Monel®, Stellite®, copper, copper-based alloy, zirconium, niobium, molybdenum, tantalum, tungsten, rhenium, platinum, platinum-based alloy, palladium, iridium, ruthenium, rhodium, osmium, titanium, vanadium, chromium, chromium-based alloy, iron, iron-based alloy, gold, silver, or aluminum, combinations of any of the foregoing, and the like. The process capsule may comprise copper, copper-based alloy, gold, silver, palladium, platinum, platinum-based alloy, iridium, ruthenium, rhodium, osmium, titanium, vanadium, chromium, chromium-based alloy, iron, iron-based alloy, nickel, nickel-based alloy, zirconium, niobium, molybdenum, tantalum, tungsten, rhenium, combinations of any of the foregoing, and the like. In one embodiment of the present disclosure, the process capsule i may be constructed of a deformable material that enables the process capsule to expand when pressurized by the at least one solvent within the capsule. In one embodiment, the support capsule is constructed to have a yield strength which, when taken in combination with the process capsule, exceeds that of the stress exerted on the capsule by the vapor pressure and temperature of a fluid (or solvent) disposed within the process capsule. In one embodiment, the support capsule has a yield strength that exceeds that of the stress exerted on the capsule by the vapor pressure and temperature of a fluid (or solvent) disposed within the process capsule. In one embodiment, the support capsule is formed from one or more materials with a higher Young's modulus than the Young's modulus of a material of the process capsule. In one embodiment, the support capsule is formed from one or more materials with a higher yield strength than the yield strength of a material of the process capsule. In a specific embodiment, the support capsule has a higher yield strength than the yield strength of the process capsule. In a specific embodiment, the support capsule has a higher Young's modulus than the Young's modulus of the process capsule. In one embodiment, the support capsule is chosen to have a yield strength that exceeds that of the longitudinal stress exerted on the support capsule by the process capsule. Additional features of the capsule are described in U.S. patent application Ser. No. 13/657,551, which is hereby incorporated by reference in its entirety.

Support capsule220comprises a relief opening218configured such that the process capsule may be deformed into the relief opening and ruptured when an internal pressure limit of the process capsule is exceeded. At least one of the size, shape and location of the relief opening may be selected to allow the process capsule to rupture when the process capsule exceeds the pressure limit. By varying at least one of the size, shape and location of the relief opening, the internal pressure at which the process capsule ruptures may be controlled. In various embodiments, Capsule220also comprises a burst disk330, described in detail below.

FIG. 3shows a burst disk assembly300, for example, for a capsule118or a capsule220. Referring toFIG. 3, relief opening320, for example, a hole, is provided in capsule support member316. Relief opening320may have a diameter between about 2 millimeters and about 200 millimeters, or between about 5 millimeters and about 50 millimeters. In certain embodiments, for example, capsule220as shown inFIG. 2, capsule support member316corresponds to support capsule sealed end216. Burst disk330is placed within relief opening320and proximate to process capsule sealed end104in such that capsule support member316supports said burst disk along an edge portion of said burst disk, leaving said interior portion of said burst disk unsupported. Burst disk330may be configured to burst when said internal pressure limit of the sealed process capsule is exceeded, causing fracture of the burst disk due to generation of a tensile stress exceeding its fracture stress and allowing said sealed process capsule to deform into the relief opening and rupture. Burst disk330may be fabricated from a ceramic, metal, cermet, glass, or single crystal material. In certain embodiments, mechanical support at periphery335is provided by a lip within relief opening320formed, for example, by counter-boring opening320from the side of capsule support member316from the side proximate to capsule sealed end104. In certain embodiments, mechanical support at periphery335is provided by a ceramic or metal cylinder held in place by a snap ring. In certain embodiments periphery335is simply supported, that is, the edge may freely rotate as the central portion of burst disk330flexes upwards due to pressure from capsule sealed end. In certain embodiments periphery335is fixed or partially fixed, that is, periphery335is rigidly attached to its support, for example, by means of a braze joint, so that the edge is inhibited from rotation as the central portion of burst disk330flexes upward due to pressure from capsule sealed end104.

During operation, a capsule such as capsule118or200is placed with a suitable high pressure apparatus. An example of such an apparatus is shown schematically inFIG. 4. Referring toFIG. 4, high pressure apparatus400and related methods for processing supercritical fluids are disclosed. In a specific embodiment, the present apparatus400includes a capsule410, a heating member or heater412, at least one ceramic ring414but can be multiple rings, optionally, with one or more scribe marks and/or cracks present. The apparatus also has a high-strength enclosure418, end flanges426,428with associated insulation, and a power control system430. The apparatus is scalable up to very large volumes and is cost effective. In a specific embodiment, the apparatus is capable of accessing pressures and temperatures of 20-2000 MPa and 400-1200° C., respectively. In a specific embodiment, the apparatus also includes a temperature controller432. Of course, there can be other variations, modifications, and alternatives.

In a specific embodiment, apparatus400comprises at least one heat zone and optionally more, such as multiple, including two or more. The heat zones include an uppermost first zone420, a growth zone422, a baffle zone424, and a charge or nutrient zone426according to a specific embodiment. When a capsule is inserted into the volume defined by a heater inner surface, an internal baffle (not shown inFIG. 4) aligns with the baffle gap zone according to a specific embodiment. The baffle defines two chambers inside the capsule, one for nutrient and one for growth according to a specific embodiment. The two chambers communicate through the perforated baffle, which can have various shapes and configurations. In the illustrated embodiment, appropriate for crystal growth when the solubility of the material to be recrystallized is an increasing function of temperature, the growth zone is located above the nutrient zone. In other embodiments, appropriate for crystal growth when the solubility of the material to be recrystallized is a decreasing function of temperature, i.e., retrograde solubility, the growth zone is located below the nutrient zone. In still other embodiments, apparatus400is approximately horizontal rather than vertical and may be fitted with a rocking mechanism (not shown). Additional details of high pressure apparatus400are disclosed in U.S. Pat. Nos. 8,097,081, 8,303,710, and 8,435,347, each of which is hereby incorporated by reference in their entirety.

It is important to note that the cell components surrounding capsule410, such as annular plug434, top end cap432and top end flange428, are not leak tight. Consequently, any pressurized fluid that escapes or is released from capsule410will be released to the environment of high pressure apparatus400. In certain embodiments, high pressure apparatus400is housed within a ventilated, primary containment structure, such as that described in U.S. Patent Application Publication No. 2011/0100291, which is hereby incorporated by reference in its entirety. In these embodiments any pressurized fluid, such as ammonia, that is released from high pressure apparatus400is contained and sent to a controlled fluid stream.

During operation, when an applied pressure P is applied to the burst disk by the outward-facing surface of capsule sealed and104, the center of burst disk330will displace outward by distance d, given approximately by

d=3⁢a416⁢t3⁢1-v2E⁢PKd(1)
where a is its radius, t is its thickness, E is its Young's modulus, ν is its Poisson's ratio, and the coefficient Kdis equal to (5+ν)/(1+ν) for simply supported boundary conditions or 1 for fixed boundary conditions, as is known in the art. The stress σ on the tensile side at the center of burst disk330is related to the applied pressure P by, approximately,

σ=3⁢a28⁢t2⁢PKσ(2)
where the coefficient Kσis equal to 3+ν if the disk is simply supported or 1+ν if the disk is fixed. When the stress exceeds the bending strength of the burst disk it will rupture, causing extrusion of a portion of capsule sealed end104into opening320followed by rupture and leaking of the pressurized fluid within interior volume114. By appropriate choice of the composition of burst disk330, its diameter, and its thickness, therefore, the capsule can be caused to fail during operation at a predetermined pressure, much like a pressure relief value or rupture disk limits the maximum pressure within a conventional pressure vessel for improved safety.

In certain embodiments, as shown inFIG. 5, piercing mechanism502, for example, comprising spike504, is provided within the unsupported volume above the burst disk330as a component of a burst disk assembly500. The spike504has the effect of forcing puncture of capsule sealed end104or capsule closed end110(seeFIGS. 1 and 2) after burst pressure disk330, if present, ruptures. In one embodiment, the gap506between the end of the piercing mechanism and the burst disk (or capsule sealed end or closed end, if the burst disk is omitted) is selected such that the process capsule is punctured and ruptured at a predetermined temperature and/or pressure. In some embodiments, the burst disk is not included. In such embodiments, at least one of the size, shape and location of the opening may be selected to allow the process capsule105to deform into the relief opening and rupture at a predetermined pressure limit. Further, a piercing mechanism502may be included where the gap506between an end of the piercing mechanism and process capsule may be selected such that the process capsule is punctured and ruptured at a predetermined pressure limit.

Referring again toFIG. 3, burst disk330may comprise a ceramic or single crystal material, such as alumina, silicon nitride, silicon carbide, zirconia, or sapphire. Other materials can also be chosen. The front and back surfaces of burst disk330may be lapped or polished. Examples of design calculations, using Eqs. (1) and (2) and published values for E, ν, and burst strength of commercially-available ceramic materials, are shown in Table 1 for a design burst pressure of 300 MPa. As is apparent from Table 1 and Eqs. (1) and (2), the burst disk assembly can be designed for a wide range of operating pressures. It is important to note that the goal of the burst disk assembly is to allow the capsule to be ruptured at a predetermined pressure and temperature. Therefore, the assembly will be designed taking into account the desired burst pressure, material and thickness of capsule wall, safe operation pressure for the capsule, and the operating temperature of the capsule.

TABLE 1Sample burst disk design calculations for a burst pressureof 300 MPa and a disk diameter of 0.375 inch (9.525 mm).FlexuralEstrengthtσdmaxtσdmaxMaterial(GPa)ν(MPa)(mm)(MPa)(mm)(mm)(MPa)(mm)sapphire4700.26906.886900.0134.216900.013Al2O33600.233609.573600.0065.913600.006Si3N43000.2810205.7310200.0313.5810200.031SiC4400.165407.735400.0104.685400.010ZrO22000.3114704.7914700.0773.0214700.076

The pressure acting on the surface of the burst disk (cf. Eqs. (1) and (2)) will be lower than the pressure inside the capsule. This is because the material of the capsule in the region directly below the burst disk transmits the pressure to the burst disk through its own deflection upwards and, this deflection depends on: (i) mechanical properties of the capsule material at the operating temperature; (ii) the pressure inside the capsule; and (iii) the ratio of the lateral dimensions of the burst area to the thickness of the capsule material (aspect ratio) at the burst location. Taking these effects into account may or may not yield to closed-form solution depending on whether the capsule material exhibits non-linear constitutive behavior (e.g., plasticity) and/or whether the aspect ratio is large enough that 3D deformation behavior can be ignored. In practice taking these effects into account may cause the designer to resort to the finite element method or other numerical techniques to engineer the burst-disk assembly. Furthermore, any uncertainty in material properties may be resolved through pressure-calibrated experiments involving several designs.

FIG. 6shows method steps that may be practiced while using a capsule for high pressure, high temperature processing. As an option, the present system900may be implemented in the context of the architecture and functionality of the embodiments described herein. Of course, however, the system900or any operation therein may be carried out in any desired environment. As shown, an operation may be implemented in whole or in part using program instructions accessible by a module. The modules can be connected to a communication path, and any operation can communicate with other operations over said communication path. The modules of the system can, individually or in combination, perform method operations within system900. Any operations performed within system900may be performed in any order unless as may be specified in the claims. The embodiment ofFIG. 6implements modules to perform: loading at least one material into an interior volume of a process capsule through a first open end, the process capsule having a first closed end and the first open end (see module920); attaching a first cap device onto the first open end of the process capsule (see module930); loading the process capsule into an interior volume of a support capsule (see module940); attaching a second cap device to a second open end of the support capsule, the support capsule having a second closed end and a second open end and a burst disk assembly (see module950); filling the interior volume of the process capsule with at least a solvent or fluid (see module960); sealing the process capsule (see module970); subjecting at least the process capsule to thermal energy to generate a supercritical fluid within the process capsule (see module980); causing formation of a crystalline material within the process capsule (see module990); removing energy from at least the process capsule (see module992); and removing material from the process capsule (see module994).