US3754529A

US3754529A - Apparatus for continuously depositing beryllia through vaporization of a basic formate

Info

Publication number: US3754529A
Application number: US00249054A
Authority: US
Inventors: P Fleischner
Original assignee: National Beryllia Corp
Current assignee: National Beryllia Corp
Priority date: 1970-06-08
Filing date: 1972-05-01
Publication date: 1973-08-28
Anticipated expiration: 1990-08-28

Abstract

An apparatus for vaporizing a basic formate of beryllium by continuous means in which the beryllium basic formate is mixed with a granular inert carrier material such as sand and as an aggregate is fed from a storage hopper through a closed screw conveyor system through a heating zone whereat the basic formate of beryllium is vaporized and in a vaporized condition is delivered to a chamber in which the beryllium basic formate is thermally decomposed into beryllia and is deposited on a substrate. The granular inert material and unvaporized basic format is discharged to a closed receiving hopper for reprocessing and the like.

Description

Unite States Patent [1 1 [111 3,754,529

Fleischner [4 Aug. 28, 1973 [54] APPARATUS FOR CONTINUOUSLY 3,414,428 12/1968 Kelly et al. 117/ 107.2 P

nerosn'mc BERYLLIA rnaoucn 3,449.1

VAPORIZATION OF A BASIC FORMATE 6/1969 Baldi 118/48 X Primary Examiner-Morris Kaplan Attorney-Ralph R. Roberts [5 7] ABSTRACT An apparatus for vaporizing a basic formate of beryllium by continuous means in which the beryllium basic formate is mixed with a granular inert carrier material such as sand and as an aggregate is fed from a storage hopper through a closed screw conveyor system through a heating zone whereat the basic formate of beryllium is vaporized and in a vaporized condition is delivered to a chamber in which the beryllium basic formate is thermally decomposed into beryllia and is deposited on a substrate. The granular inert material and unvaporized basic formate is discharged to a closed receiving hopper for reprocessing and the like.

7 Claims, 3 Drawing Figures APPARATUS FOR CONTINUOUSLY DEPOSITING BERYLLIA THROUGH VAPORIZATION OF A BASIC FORMATE DIVISIONAI. APPLICATION This is a Divisional Application of Application Ser. No. 44,344 filed June 8th, 1970, now U.S. Pat. No. 3,679,463, in the name of the present Applicant.

DESCRIPTION OF THE PRIOR ART The particular physical qualities of BeO has made the dense coating of substrates with BeO highly desirable and commercially used. One method or process for producing such a dense coating of BeO is disclosed in U.S. Pat. No. 3,484,278 which issued Dec. 16th, 1969, with TABEL and HOEKSTRA as inventors. As seen in FIG. 1 of this patent, the reduction to practice and teaching discloses known laboratory equipment such as a bell jar. The resulting coating of substrates is satisfactory as to its composition, structure and use, but from an economical standpoint the labor cost per piece exceeds the desired practical level. It is also to be noted that all exposed surfaces within the bell jar 10 are given substantially the same amount of deposition of BeO. On the substrates to be plated this is desirous; on the equipment including the inside of the bell jar this is not only a waste, but often requires removal before the equipment can again be used. The information and description provided in U.S. Pat. No. 3,484,278 aboveidentified is incorporated by reference into this application.

Conveying systems are of course well known and certain processing systems are representatively shown in U.S. Pat. No. 3,176,970 to HOLCROFT of Apr. 6th, 1965 and in U.S. Pat. No. 3,497,914 to TYBOUT of Mar. 3rd, 1970. In these and other systems, insofar as is known, there is no showing of a closed conveyor system wherein in one portion there is provided a heating region whereat the metal is vaporizedand collected and then is conducted or transported to a deposition chamber wherein the wall is made porous so as to enable passage therethrough of pressurized dry air and the like. This pressurized gas is forced inwardly through the wall so that the vaporized beryllium basic formate is prevented from coming in contact with the wall or walls of the deposition chamber.

Deposition chambers for gas or vapor plating are representatively shown in U.S. Pat. No. 2,905,573 to MARVIN issuing Sept. 22nd, 1959; U.S. Pat. No. 2,921,868 to BERGER issuing Jan. 19th, 1960, and in U.S. Pat. No. 2,929,739 to BREINING et al., issuing Mar. 22nd, 1960. These and other patents show tubular inner chambers but, insofar as is known, the use of pressurized dry air or gas through a porous inner wall of a chamber to maintain the inner wall surface in an uncoated condition is novel and provides a means for commercial coating of substrates with dense beryllia.

SUMMARY OF THE INVENTION The present invention may be summarized at least in part with reference to its objects. It is an object of this invention to provide an apparatus for continuously producing a beryllium basic formate vapor by heating an aggregate containing a portion of basic formate of be ryllium as the aggregate is transported by a screw conveyor through a heating zone. This formate vapor is collected in a hood chamber and from this chamber is fed through a conductor or pipe to a chamber in which the substrates to be coated are placed.

It is a further object of this invention to provide an apparatus for producing and depositing beryllia on substrates in which a basic formate of beryllium is mixed with an inert granular material such as sand and by and in a closed conveyor system is brought to and through a heating zone whereat the basic formate of beryllium is vaporized and in a gaseous condition is fed to a deposition chamber in which substrates are placed for thermally decomposing beryllium basic formate to provide hard dense beryllia deposits on a substrate heated to a temperature of 250-600 C. The inner walls of the deposition chamber are of a porous construction to the extent that dry air, gas and the like may be forced through the porous wall to provide a gas liner or curtain inhibiting the deposition of the beryllia on the inner surface pf the chamber walls.

In the apparatus to be more fully described hereinafter, a beryllium basic formate is mixed with a granular inert material such as sand. The mixture is preferably about 5 to 10 percent basic formate by weight with the balance an inert carrier material such as sand. From a hopper, this mixture is discharged to a screw conveyor which is sealed except for the inlet from the hopper and an outlet into a sealed vertical discharge chute to the inlet end of yetanother sealed screw conveyor. Towards the discharge end of this conveyor, the trough walls are made porous and are enclosed in a heat zone of chamber provided to locally heat this area to 150 to 300 centigrade. This temperature is sufficient to vaporize the basic formate of beryllium at an to percent efficiency. The vapor passes through the porous passageways while residue granular ash and sand are discharged at the end of the conveyor into a sealed chute and into another sealed conveyor to discharge into another sealed chute and sealed hopper where it is accumulated for disposal or reprocessing.

The vaprozied basic formate of beryllium is collected in an aspirating chamber above the conveyor and from this chamber is fed by a tubular conductor to a deposition chamber having an inner wall of a porous construction. The vapor is fed to and into this inner chamber so as to be brought in way of the substrate to be coated. The outer portion of the deposition chamber is fed with pressurized dry air or the like which is permitted to flow in a determined amount through the porous wall so as to push the vaporized basic formate of beryllium delivered into the inner chamber from any plating contact with the wall of the inner chamber.

INTENT OF THE DISCLOSURE V There has been chosen a specific embodiment of the apparatus for continuously vaporizing a basic formate of beryllium and through a conductor feeding this vapor to a preferred deposition chamber for plating substrates with dense BeO. This specific embodiment has been chosen for the purposes of illustration and description as shown in the accompanying drawings wherein:

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 represents a somewhat schematic side view of a preferred conveying and vaporizing apparatus of this invention;

FIG. 2 represents an enlarged sectional side view of a deposition chamber adapted for transmitting a vaporspecification discloses certain details of construction for the purpose of explanation of the broader aspects of the invention, but it should be understood that structural details may be modified in various respects without departures from the concept and principles of the invention and that the invention may be incorporated in other structural forms than shown.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the schematic side view of FIG. 1 it is to be noted that a conveying and vaporizing apparatus includes a base 10 upon which a support 11 carries a hopper 12 within which is stored an aggregate 13 consisting of a basic formate of beryllium and a granular inert carrier material such as sand. This hopper is provided with a discharge chute 14 disposed to control the flow of aggregate material from hopper 12 to a screw conveyor 16 diven by a motor 18 through coupling shaft 20. The housing 21 for the conveyor 16 is sealed with the rear end of the conveyor housing 21 having a closed end member 22 to prevent any gas back up or dust from the conveyor 16 to and out the rear end of the conveyor as beryllium compounds and their va-' pors are highly toxic. A bearing 24 supports the conveyor l6 and is mounted on a closed right end of the housing 21. The screw 16 in this conveyor is a choked auger type designed so that the choked auger fills the flutes of the screw to act as a gas seal to prevent any vapor from flowing back and into the hopper. When the aggregate in the conveyor reaches the discharge outlet at the right end, the housing 21 is substantially full. Attached to the discharge end of the conveyor 16 is a drop chute 26 through which the aggregate is fed downwardly to yet another screw conveyor also of a closed type. The conveyor is driven by means of a motor 27 through shaft 28 coupled to the shaft of conveyor 30 disposed to carry the aggregate rightwardly as indicated by the arrow. The housing 32 has its left or drive end particularly closed or sealed with a cap end 34 adapted to prevent any escape of any vapor or dust to andout the conveyor. Intermediate the ends of the conveyor 30 there is provided a closed heating chamber 40 which is sealed to housing 32. In this chamber the aggregate containing the basic formate of beryllium is heated to a determined degree which is contemplated to be one hundred fifty to three hundred degrees centigrade. This aggregate is transported by screw 30 so as to be fed through this heating chamber 40 with the beryllium basic formate heated sufficiently to vaporize as described in US. Pat. No. 3,484,278 above-identified. The vaporized beryllium basic formate is collected in an upper chamber 42 from whence it is conducted by a duct 44. The conveyor screw 30 carries the aggregate into the chamber 40 wherein the screw is continued but the housing 32 is terminated and becomes an open top trough 41. The trough 41 is preferably constructed of porous metal through which heated dry air is passed to vaporize and transport the beryllium basic formate from the aggregate passing along the screw conveyor. The metal trough 41 opens into upper chamber 42 which is an aspirating chamber with duct 43 carrying pressurized gas or air which is discharged into the vapor conveying duct 44. The aspirating chamber creates a negative pressure above the trough 41 so that the subliming material as it is volatilized is drawn to duct 44.

After the basic formate of beryllium has been vaporized in heating chamber 40 the residue containing some organic ash with the balance mainly sand or like inert material is caused to be moved into the closed conveyor 46 and to drop through discharge chute 48 into a return screw conveyor 50 of closed construction and driven by motor 51. The aggregate is delivered for discharge into a drop chute 52 and then into closed accumulating container 54 where it is retained in a sealed condition until disposal or reclaimation is to be made. Like conveyor 16 the return screw conveyor 50 is of the choked auger type which receives the residue from chute 48 and before discharge through chute 52 the residue fills the conveyor housing. The filled flutes of the choked auger act as a gas seal to prevent any vapor from flowing into accumulating container 54.

DEPOSITION CHAMBER OF FIGS. 2 AND 3 Referring now to FIGS. 2 and 3 there is shown a deposition chamber 55 where vaporized basic formate of beryllium from the heating chamber 40 is fed through duct 44 into an inner chamber area 60 in which substrates 62 to be plated are placed. An inner wall 64 is preferably of a porous composition and in the preferred embodiment is shown as a tube. Through this wall dry air and/or any of several gases such a nitrogen, oxygen and the like may be caused to flow under the influence of a determined amount of pressure. Inner wall 64 is supported and enclosed by an outer housing 66 having end walls so disposed as to provide a closed gas chamber area 68. Baffles or partitions 69 are attached to and are carried by outer housing 66 so as to provide conveying passageways for the controlled flow of gas in chamber 68. The baffles may be in the nature of plates radially arranged in a longitudinal array as in FIG. 3 or, if desired, may be helically arranged or may be arranged in other combinations or configurations providing for a desired controlled gas flow. These baffles may be contoured on their inner faces to provide a support for tube 64. One or more inlets 70 are provided in outer housing 66 so that the pressurized dry air, gas and the like can be fed to the several closed gas chamber areas. An outlet 72 is provided at the end of inner wall 64 which is opposite duct 44 providing the inlet for the vaporized basic formate of beryllium to the inner chamber.

USE AND OPERATION In the apparatus as shown in FIGS. 1 through 3 and above-described, an initial aggregate of basic formate of beryllium is mixed with an inert granular material such as sand. The inert material acts as a carrier for the basic formate and for the granular ash after to percent of the basic formate of beryllium has been vaporized. The system is sealed at one end by the choked conveyor 16 so that the vapor flow will be caused to go into duct 44 rather than back into the hopper, and so that no dust or vapor can escape to endanger the operator of the equipment. This aggregate is stored in hopper 12 from which it is fed through a metering discharge chute 14 to a first conveyor 16. This conveyor is sealed as to its housing and the flow of aggregate in the conveyor is sealed by a high level choked auger to prevent any back flow of heated air, vapor and the like from subsequent operations.

From conveyor 16 the aggregate is fed through chute 26 to the conveyor 30 which is driven by motor 27 and carries the aggregate into the heating zone of chamber 40. This portion of the conveyor is disposed to spread and agitate the aggregate so that as it is brought into the porous heated trough 41 it is heated as evenly as possible. The vaporized basic formate of beryllium is drawn into chamber 42 and is then fed to deposition chamber 55 through flue conductor 44. The residue in conveyor 30 is fed into conveyor section 46 from whence it is discharged into chute 48 into return conveyor 50. This conveyor is a choked auger preventing any gas flow to subsequent discharge operations and is of a length and size disposed to cool the residue a determined amount before it is discharged into chute 52 and accumulating container 54.

The vaporized basic formate of beryllium fed to de position chamber 55 is brought to and into the inner chamber 62 which is at a temperature of two hundred fifty to six hundred degrees centigrade. To prevent the deposition of BeO on the inner surface of wall of tube 64 the vaporized basic formate of beryllium is urged from engagement with the wall by means of dry air, nitrogen, oxygen or other gaseous mixtures. This flow through the wall provides a gas flow normal to the inner wall of tube 64 tending to keep the vaporized basic formate from engagement with the wall. That vaporized beryllium basic formate not deposited on the heated substrates 62 in the inner chamber is fed with the gas flowing through the wall to and out exit 72 to a reclaiming process or disposal.

Electronic sensors and controls providing determined rates of flow of the aggregate and residue and heating temperatures for both heating chamber and deposition chamber as well as many other controls have been omitted from the above drawing and description as these are known components whose selection and use are determined by the circumstances of the particular operation and result. Although the

conveyors

16 and 50 are preferably of the choked auger construction it is also to be noted that conveyors with metering bulkhead construction may be used to provide the desired upper seal of the conveyor.

The apparatus above-described has been reduced to practice and extensively and successfully used in vaporizing beryllium basic formate. The basic disclosure of the sublimation of a solid chemical compound as is beryllium basic formate is shown in U.S. Pat, No. 3,484,278 but the apparatus of this invention may be used for other solid sublimable chemical compounds. Examples of said other solid sublimable chemical compounds are beryllium acetyl acetonate and acetylacetonato (1,5-cyclooctadiene) iridium. Any oxide of metal or metal alloy can be deposited by the vapors or organo metallic compounds such as metal alkyates, carboxylates and phenolates. Further compounds are identified in a book entitled, Decomposition of Organo Metallic Compounds to Refactory Ceramics, Metals and Metal Alloys". Edited by K. S. Mazdiyasni, published by the University of Dayton Press, (Dayton, Ohio), copyright 1968.

The deposition chamber of FIG. 2 is to be particularly noted. In this chamber pressurized gas or air is passed through the porous wall 64 to prevent unwanted deposition of the vaporized organo-metalloid product on the inner walls of porous member 64. Conveying means for the to-be-coated product 62 has not been shown as such means is more-or-less conventional in that the product to be moved and coated will influence the means selected. The heating chamber 40 and conveyor section 41 are also constructed in accordance with the characteristics of the infeeding material and the necessary rate of production of the vaporized compound.

Terms such as left, right", up, down, bottom, top", front", back", "in, out and the like are applicable to the embodiment shown and described in conjunction with the drawing. These terms are merely for the purposes of description and do not necessarily apply to the position in which the apparatus for continuously producing and depositing vaporized basic formate of beryllia may be constructed or used.

The conception of the vaporization and deposition apparatus and its application is not limited to the specific embodiment shown but departures therefrom may be made within the scope of the accompanying claims and without sacrificing its chief advantages and protection is sought to be the broadest extent the prior art allows.

What is claimed is:

1. Apparatus providing for a determined continuous production of a vaporized solid sublimable organometalloid compound such as beryllium basic formate, beryllium acetyl acetonate and the like, said apparatus providing for the delivery of said vaporized material to a deposition chamber, said apparatus including: (a) a hopper providing for the closed storage of an aggregate which includes a solid sublimable organo-metalloid compound mixed with a granular inert carrier material; (b) a first conveyor of closed construction disposed to receive a controlled flow of said aggregate. through a portion of said first conveyor so as to fill substantially all available passage area so that the aggregate at this slowed portion will provide a gas seal to the flow of vapor through said conveyor; (d) a second conveyor of closed construction and disposed to receive the discharge of aggregate from the first conveyor, said second conveyor disposed to feed said aggregate through a closed heating chamber wherein the solid sublimable organo-metalloid compound is heated sufiiciently to vaporize, (e) a collection chamber in flow communication with the heating chamber and disposed to receive the vapors from the heating chamber; (f) means to conduct the vapors from the collection chamber to a deposition chamber; (g) a third conveyor of closed construction disposed to receive the residue from the heating chamber and transport said residue through a portion of said third conveyor; (h) means for slowing the flow of residue through the third'conveyor so that substantially all available passage area is filled to provide a gas seal to the flow of vapor through said conveyor,

and (i) an accumulating closed container disposed to receive the residue from the heating chamber and said third conveyor.

2. Apparatus for the production of a vaporized solid sublimable organo-metalloid compound as in claim 1 in which the means for slowing the flow of material through the first and third conveyors is by means of a screw conveyor having a choked auger construction.

3. Apparatus for the production of a vaporized solid sublimable organo-metalloid compound as in claim 1 in which the means for slowing the flow of material through the first and third conveyors is by means of a screw conveyor passing a metering bulkhead construction.

4. Apparatus for the production of a vaporized solid sublimable organo-metalloid compound as in claim 1 in which the closed heating chamber includes a trough of porous metal through and around which heated dry air is forced so as to vaporize the solid sublimable organometalloid compound and drive the vapor from the aggregate. v

5. Apparatus for the production of solid sublimable organo-metalloid compound as in claim 4 in which the collection chamber has one side open to the heating chamber, said collection chamber being operated at a negative pressure so that the vaporized solid sublimable organo-metalloid compound may be moved to and through a duct to an inner chamber area of the deposition chamber.

6. Apparatus for the production of a solid sublimable organo-metalloid compound as in claim 5 in which the deposition chamber has an inner wall of porous construction surrounded by a closed gas chamber supplied with pressurized gas, air and the like, said gas being permitted to flowthrough the porous inner wall at a rate sufficient to keep the vaporized solid sublimable chemical compound from engagement with the inner surface of the porous inner wall.

7. Apparatus for the production of a vaporized solid sublimable organo-metalloid compound as in claim 6 in which the closed gas chamber is provided with baffles sposed to direct the flow of pressurized gas in a deterined path

Claims

2. Apparatus for the production of a vaporized solid sublimable organo-metalloid compound as in claim 1 in which the means for slowing the flow of material through the first and third conveyors is by means of a screw conveyor having a choked auger construction.
3. Apparatus for the production of a vaporized solid sublimable organo-metalloid compound as in claim 1 in which the means for slowing the flow of material through the first and third conveyors is by means of a screw conveyor passing a metering bulkhead construction.
4. Apparatus for the production of a vaporized solid sublimable organo-metalloid compound as in claim 1 in which the closed heating chamber includes a trough of porous metal through and around which heated dry air is forced so as to vaporize the solid sublimable organo-metalloid compound and drive the vapor from the aggregate.
5. Apparatus for the production of solid sublimable organo-metalloid compound as in claim 4 in which the collection chamber has one side open to the heating chamber, said collection chamber being operated at a negative pressure so that the vaporized solid sublimable organo-metalloid compound may be moved to and through a duct to an inner chamber area of the deposition chamber.
6. Apparatus for the production of a solid sublimable organo-metalloid compound as in claim 5 in which the deposition chamber has an inner wall of porous construction surrounded by a closed gas chamber supplied with pressurized gas, air and the like, said gas being permitted to flow through the porous inner wall at a rate sufficient to keep the vaporized solid sublimable chemical compound from engagement with the inner surface of the porous inner wall.
7. Apparatus for the production of a vaporized solid sublimable organo-metalloid compound as in claim 6 in which the closed gas chamber is provided with baffles disposed to direct the flow of pressurized gas in a determined path