DR. MEHRDAD YASREBI
Medical Practice at 122 Ave, Portland, OR

6619368, Sep 16, 2003

Jun 26, 2000

09/602671

Mark E. Springgate - Portland OR
James R. Barrett - Milwaukie OR
David Howard Sturgis - Boring OR
Douglas G. Nikolas - Battleground WA
Mehrdad Yasrebi - Clackamas OR

PCC Structurals, Inc. - Portland OR

B22D 102

164 41, 164 761, 164517, 164519

A method for imaging inclusions in metal or metal alloy castings is described. One embodiment of the present method first involves casting a metal or metal alloy article using an investment casting mold where the mold facecoat, and perhaps one or more of the mold backup layers, comprises an imaging agent distributed substantially uniformly throughout in amounts sufficient for imaging inclusions. The facecoat preferably comprises an intimate mixture of a refractory material and the imaging agent. Intimate mixtures can be produced in a number of ways, but a currently preferred method is to cocalcine the refractory material, such as yttria, with the imaging agent, such as gadolinia. The facecoat also can comprise plural mold-forming materials and/or plural imaging agents. The difference between the linear attenuation coefficient of the article and the linear attenuation coefficient of the imaging agent should be sufficient to allow imaging of the inclusion throughout the article. The metal or metal alloy article is then analyzed for inclusions by N-ray analysis.

6390179, May 21, 2002

Nov 8, 2000

09/710545

Mehrdad Yasrebi - Clackamas OR
David Howard Sturgis - Boring OR
Michael Gerald Sorbel - Oregon City OR
Mark E. Springgate - Portland OR
Douglas Gene Nikolas - Battleground WA

PCC Structurals, Inc. - Portland OR

B22C 900

164519, 164 15, 164517, 106 3827

Methods for increasing the lifetime of a casting slurry are described. One feature of the invention is processing refractory powders at a first hydration level to produce powders having a second, lower hydration level before the processed materials are used to form casting slurries. Processing according to the disclosed methods results in a substantial increase in the lifetime of a slurry made using such processed materials compared to slurries made using materials not processed as described herein. One embodiment of the method comprises heat processing at least one refractory powder, typically refractory powders which have undergone hydration subsequent to commercial production, for a period of time sufficient to reduce the amount of hydration from a first hydration level to a second hydration level. A slurry is formed using the refractory powder at an hydration level which provides an increased slurry lifetime relative to the same material without processing according to the method of the present invention. Slurry formation can be accomplished substantially immediately after processing, or up to about one week after processing, typically less than 24 hours after processing, and even more typically within 2 hours to about 8 hours after processing.

5624604, Apr 29, 1997

May 9, 1994

8/239706

Mehrdad Yasrebi - Clackamas OR
William W. Kemp - Milwaukie OR
David H. Sturgis - Gladstone OR
Ilhan A. Aksay - Princeton NJ
Hamazo Nakagawa - Ube City, Yamaguchi 755, JP

B01J 1300, C04B 3504, C04B 35505, C09C 308

2523131

A method for dispersing and reducing the rate of dissolution and/or hydration of colloidal ceramic suspensions is described. The method comprises adding to a ceramic suspension a non-polymeric hydroxylated organic compound. The organic compound has at least one hydroxyl group, preferably at least two hydroxyl groups. The organic compound also includes a functional group selected from the group consisting of a carboxyl, a carboxylate, a sulfonic acid, a sulfonate, a phosphoric acid, a phosphate, an amine, and a quaternary ammonium salt. The ceramic suspension typically comprises a colloidal suspension of a metal oxide, wherein the metal of the metal oxide is an alkali metal, alkaline-earth metal or a rare-earth metal, but preferably is magnesium, calcium or a rare-earth metal. The non-polymeric organic compound is added to the suspension in an amount effective to substantially disperse and reduce the rate of dissolution of the ceramic particles, such as from about 0. 01 weight percent to about 5.

6920913, Jul 26, 2005

May 7, 2003

10/431881

Mehrdad Yasrebi - Clackamas OR, US
David Howard Sturgis - Boring OR, US
Michael Gerald Sorbel - Oregon City OR, US
Mark E. Springgate - Portland OR, US
Douglas Gene Nikolas - Battleground WA, US

PCC Structurals, Inc. - Portland OR

B22C001/02

164517, 164519

Embodiments of a method for increasing the lifetime of a casting slurry are described. One feature of the disclosed embodiments comprises processing refractory materials that are used to form casting slurries to provide a substantial increase in slurry lifetime for slurries made using such processed materials compared to slurries made using materials not processed as described herein. One embodiment of the method comprises heat processing at least one refractory powder. Without limiting the invention to a theory of operation, processing is continued for a period of time sufficient to reduce the amount of hydration from a first hydration level to a second hydration level. A slurry is formed using the refractory powder at a hydration level which provides an increased slurry lifetime relative to the same material without processing according to the disclosed embodiments.

6024163, Feb 15, 2000

Jan 7, 1997

8/779641

Mark Edwin Springgate - Portland OR
Douglas Gene Nikolas - Battleground WA
David H. Sturgis - Boring OR
Mehrdad Yasrebi - Clackamas OR

Precision Castparts Corp. - Portland OR

B22C 102, B22C 902

164519

Investment casting shells, methods for their manufacture and methods for casting metals and alloys using such shells are disclosed. One feature of the shells is that the facecoat plus interior backup layers are purposefully designed to have substantially similar coefficients of thermal expansion to the seal dip layers. This helps reduce the occurrence of dimensional casting defects caused by differential thermal expansions of the layers comprising the shell. One embodiment of such a shell comprises a facecoat, plural interior backup layers and plural intermediate backup layers wherein at least one of the plural intermediate backup layers comprises a material capable of undergoing a volumetric transformation during cool down, and wherein the seal-dip layers have a coefficient of thermal expansion that varies from the coefficient of thermal expansion of the facecoat and interior backup layers by less than about 10 percent. A particular embodiment of the method is useful for investment casting aluminides, particularly TiAl, using a shell having an alumina facecoat.

5643844, Jul 1, 1997

Sep 27, 1994

8/312694

Mehrdad Yasrebi - Clackamas OR
Mark Edwin Springgate - Portland OR
Douglas Gene Nikolas - Battleground WA
William Warren Kemp - Milwaukie OR
David Howard Sturgis - Gladstone OR
Renee Van Ginhoven - Seattle WA

Precision Castparts Corporation - Portland OR

C04B 35505

501152

Time-stable yttria slurries, and a method for forming such yttria slurries and articles therefrom are described. The method involves forming an intimate mixture comprising yttria and at least about 0. 1 weight percent of a dopant material. An aqueous slurry is then formed comprising from about 1 weight percent to about 95 weight percent of the intimate mixture. The intimate mixture may be formed by heating the mixture to a temperature sufficient to calcine the mixture. Alternatively, the intimate mixture may be formed by heating the mixture to a temperature sufficient to fuse the mixture. The dopant also may be provided as a surface coating on the yttria particles. The dopant material comprises an oxide or hydroxide, or combinations thereof, or compounds that form such oxides or hydroxides upon further processing, wherein the metal oxides or hydroxides are of metals selected from the group consisting of aluminum, titanium, niobium, tantalum, silicon, hafnium, tin, gallium, indium, beryllium, thorium, boron, scandium, vanadium, chromium, ruthenium, rhodium, iridium, palladium, platinum, copper, germanium, bismuth, tellurium, erbium, thulium, ytterbium, lutetium, neptunium, plutonium, and combinations thereof. The aqueous suspension may further comprise other materials, such as other ceramic or metallic particles, co-solvents, dispersing agents, surfactants, inorganic binders, or organic binders.

6102099, Aug 15, 2000

Dec 15, 1998

9/212116

David Howard Sturgis - Boring OR
James R. Barrett - Milwaukie OR
Mark E. Springgate - Portland OR
Mehrdad Yasrebi - Clackamas OR
Douglas G. Nikolas - Battleground WA

PCC Structurals, Inc. - Portland OR

B22C 102, B22C 904

164 41

A metal or metal alloy article is cast using an investment casting mold where the mold facecoat, and perhaps one or more of the mold backup layers, comprises an imaging agent distributed substantially uniformly throughout in amounts sufficient for imaging inclusions. The facecoat preferably comprises an intimate mixture of a refractory material and the imaging agent. Intimate mixtures can be produced in a number of ways, but a currently preferred method is to cocalcine the refractory material, such as yttria, with the imaging agent, such as gadolinia. The facecoat also can comprise plural mold-forming materials and/or plural imaging agents. The difference between the linear attenuation coefficient of the article and the linear attenuation coefficient of the imaging agent should be sufficient to allow imaging of the inclusion throughout the article. The metal or metal alloy article is then analyzed for inclusions by N-ray analysis. The method also can include the step of analyzing the metal or metal alloy by X-ray analysis.

5464797, Nov 7, 1995

Dec 5, 1994

8/349257

Mehrdad Yasrebi - Clackamas OR
William W. Kemp - Milwaukie OR
David H. Sturgis - Gladstone OR
Douglas G. Nikolas - Battleground WA
Gary L. Wright - Brush Prairie WA
Thomas J. Kelly - Gresham OR
Mark E. Springgate - Portland OR
Ted R. Crego - Gladstone OR

Precision Castparts Corporation - Portland OR

C04B 35505, C22C 100, C22C 300

501103

The disclosure describes an aqueous ceramic slurry having from about 70-weight percent to about 85 weight-percent of a fused yttria-zirconia material. The weight percent of zirconia in the fused yttria-zirconia preferably varies from about 1. 0 weight percent to about 10. 0 weight percent. Fused slurries may comprise, in addition to fused yttria-zirconia, an inorganic binder (preferably silica), an organic binder (preferably a latex binder), a surfactant (preferably a sodium dioctyl sulfosuccinate), an antifoaming agent (preferably a water-dilutable active silicone defoamer) and titanium dioxide. The slurries of the present invention are used to form ceramic mold facecoatings for casting reactive materials. These slurries are less sensitive to pH fluctuations than are slurries made from 100 percent yttria (yttria slurries). Moreover, slurries as described in the disclosure do not gel prematurely, and exhibit substantially the same formation of oxygen-enriched titanium (alpha case) than do yttria slurries.

5407001, Apr 18, 1995

Jul 8, 1993

8/089259

Mehrdad Yasrebi - Clackamas OR
William W. Kemp - Milwaukie OR
David H. Sturgis - Gladstone OR
Douglas G. Nikolas - Battleground WA
Gary L. Wright - Brush Prairie WA
Thomas J. Kelly - Gresham OR
Mark E. Springgate - Portland OR
Ted R. Crego - Gladstone OR

Precision Castparts Corporation - Portland OR

B22C 106, B22C 904

164519

The disclosure describes an aqueous ceramic slurry having from about 70-weight percent to about 85 weight-percent of a fused yttria-zirconia material. The weight percent of zirconia in the fused yttria-zirconia preferably varies from about 1. 0 weight percent to about 10. 0 weight percent. Fused slurries may comprise, in addition to fused yttria-zirconia, an inorganic binder (preferably silica), an organic binder (preferably a latex binder), a surfactant (preferably a sodium dioctyl sulfosuccinate), an antifoaming agent (preferably a water-dilutable active silicone defoamer) and titanium dioxide. The slurries of the present invention are used to form ceramic mold facecoatings for casting reactive materials. These slurries are less sensitive to pH fluctuations than are slurries made from 100 percent yttria (yttria slurries). Moreover, slurries as described in the disclosure do not gel prematurely, and exhibit substantially the same formation of oxygen-enriched titanium (alpha case) than do yttria slurries.