3,473,999 United States Patent O" ice Patented Oct. 21, 1969

l 2 sion of the vitreous seal to a thermally controlled crystal 3,473,999 lized seal. GLASS 0R METAL SURFACES SEALED It will be appreciated by those versed in the subject BY Si02-Al2O3-WlgO COMPOSHTIONS AND art that the above-mentioned complicated procedures are METHOD OF MAKING difficult to effect, time consuming and expensive and, if Gordon M. Mnchow, Sylvania, Ohio, assignor to Owens llllinois, l[nc., a corporation of Ohio composite articles can be ‘fabricated and seals compound No Drawing. Continuation-impart of application Ser. No. ed by a procedure which essentially eliminates the dis 567,350, July 25, 1966. This application Nov. 5, 1968, advantages associated with the prior art, such procedure Ser. No. 773,667 would have a de?nite commercial value to the present art. Int. Cl. B32b 17/06, 15/04 Likewise, it will be appreciated by those skilled in the in US. Cl. 161-193 17 Claims stant art that if articles of commerce and science made of both clear and opaque parts and thermally crystallized seals can be effected by a relatively simple procedure that ABSTRACT OF THE DISCLOSURE does not require a multi-step procedure of heating in A borosilicate glass or metal or metal alloy having a elaborate ovens at carefully controlled temperatures, such surface sealed or bonded to a thermally crystallized glass novel procedure would, in addition to its commercial ceramic composed essentially of from 40-70 weight per value, also represent an improved and useful contribu cent of SiO2, 15—35 weight percent A1203 and 5-15 weight tion to the art. percent MgO and which may include 0-20 weight percent Accordingly, it is an object of the present invention to ZrOZ, 0-5 weight percent TiOZ and 0-3 weight percent overcome the difficulties associated with the prior art. LizO and which is prepared by a method which involves Another object of the present invention is to utilize applying the glass-ceramic while in a non-crystallized glass compositions which permit use of a simple heat pro state to the borosilicate glass, metal or metal alloy sur cedure to effect sealing and thermal crystallization. face or surfaces to which it is to be sealed or bonded Yet another object of the instant invention is to provide and thereafter subjecting the glass-ceramic to a tempera an easy method for fabricating composite articles of man ture at least as high as its melting temperature to effect a ufacture made of both clear and opaque parts. thermal crystallization and bonding thereof to the sur Still a further object of the present invention is to ef face to which it was applied. fect composite articles of science and commerce consisting of both clear and opaque parts by joining a glass-ceramic 30 composition to a borosilicate glass by means of a relative ly simple inventive heat method. RELATED APPLICATIONS Still another object of the present invention is to pro vide glass-to-metal seals. The present application constitutes a continuation-in Still a further object of the present invention is to pro part of copending US. patent application Ser. No. 567, vide a method of joining borosilicate glasses to metals by 350 previously ?led by applicant herein on July 25, 1966 means of a sealing glass consisting of a glass-ceramic ma and now abandoned. terial through a relatively simple heat procedure. BRIEF SUMMARY OF THE INVENTION Other objects, features and advantages of this invention will become evident from the following detailed descrip The present invention pertains to the manufacture of tion of the manner and mode of practicing the invention. composite articles formed by joining together, with a DETAILED DESCRIPTION OF THE INVENTION glass-ceramic sealing glass, parts made of glass or metal. More particularly, the instant invention relates to novel In attaining the objects, features and aspects of the means for fabricating glass objects consisting of clear present invention, it has now been unexpectedly discov and opaque parts and to a novel means for making glass ered that glass-ceramic materials can be be effectively to-metal seals. Speci?cally, the subject invention relates employed as sealing glasses by a simple heat procedure to to joining borosilicate glasses to glass-ceramic materials fabricate seals between borosilicate glasses, borosilicate to fabricate items of commerce of both clear and opaque glasses and metals, and for manufacturing composite arti parts and to a method for bonding borosilicate glasses to cles of commerce and industry wherein said items are made of both clear and opaque parts. metals. A dual need exists for an economical and useful way The glass-ceramic materials employed for the purpose of making glass articles of science and commerce consist of the present invention are formulated as a “base glass ing of both clear and opaque parts and for fabricating comprising silica (SiO2), alumina (A1203), and magnesi glass-to-metal seals. Generally, in the prior art, various um oxide (MgO). Various amounts of zirconia (ZrO2), articles made of both clear and opaque parts were ef titanium dioxide (T102), and lithium oxide (LiZO‘) can fected by joining a vitreous, thermally crystallizable glass be incorporated in the base glass-ceramic composition to another or base glass by a rate controlled process as utilized by the subject invention. Speci?cally, the base far as the former glass was concerned. The manufacturing composition employed in the instant invention comprises procedure employed usually involved the complicated about 40 to 70 weight percent SiO2, 15 to 35 weight per multiple steps of forming a vitreous joining followed by 60 cent Al2O3, and 5 to 15 weight percent MgO. The pres a speci?ed sequence of controlled and regulated heat treat ently preferred compositional ranges for the base glass ments which resulted in the conversion of the vitreous comprises about 40 to 60 weight percent SiO2, 16 to 32 glass to a thermally crystallizable material to effect an weight percent A1203, and 6 to 12 weight percent MgO. article of both clear and opaaque parts. Also to the base glass-ceramic employed herein can be The manufacture of glass-to-metal seals also involved added from O to 20 weight percent ZrO2, 0 to 5 weight a complicated multi-step procedure requiring the joining percent TiOg, and 0 to 3 weight percent LizO, with a of the sealing glass to the metal and base glass that is to presently-preferred range for the latter three oxides of be sealed or bonded together to effect a vitreous seal. 5 to 15, 2 to 5, and 1 to 3 weight percent respectively. After the vitreous seal was molded, a controlled heat Illustrative base glass-ceramic compositions of the pres treatment or heat process was employed for the conver ent invention are set forth in Table I. 3,473,999

TABLE I Percent By Weight Exam- Exam- Exam- Exam- Exam- Exam ple 1 ple 2 ple 3 ple 4 ple 5 ple 6 Ingredients: ZrO 5. 0 7. 5 10. 0 12. 0 ______Tl02__ ...... - _ 3. 6 SiOg- _ 53. l 51. 7 50. 4 49. 3 69. 7 A1203_ 30. 0 29. 2 28. 4 27. 7 16. 8 MgO ______ll. 9 11. 6 11. 2 11. 0 7. 2 LigO ______. 2. 7 Liquidus, ° F ______.- 2, 695 >2,765 >2, 765 >2, 765 2,300

The glass-ceramic sealing compositions employed ganic binder should not react with any of the elements herein can be made from conventional commercially making up the bonded assembly. As examples of other available batch ingredients and by standard melting and organic binders which, among others, can be used are forming procedures. The batch consisting of MgO, such organic binders as gelatine dissolved in water, nitro A1203, SiOz, and other oxides is conveniently melted by cellulose and butylacetate, camphor with cellulose nitrate, any standard glass melting procedures and apparatus. and the like. The melting temperature used to effect the compositions The following examples are merely illustrative of the is between about 2600° F. to 3000° F. The glass-ceramic 20 present invention and are not to be construed as limit sealing compositions utilized for the subject invention ing the spirit and scope of the invention in any man can be made from the batch ingredients and in accord ner, as these and other variations will be readily appar ance with the melting and forming procedures disclosed ent to those versed in the subject art. in US. Patent No. 3,117,881. This patent further dis EXAMPLE 7 closes a unique heat treatment through successive stages 25 to e?ect in situ crystallization, while the present inven A length of Kovar alloy consisting of 29v percent tion comprises an-unexpected means for accomplishing in nickel, 17 percent cobalt, 0.3 percent manganese and the situ crystallization by means of an ordinary ?ame. balance iron was intimately bonded to a glass-ceramlc The borosilicate glass compositions that can be em composition consisting of 10 weight percent Z102, 50.4 ployed within the mode and manner of the present inven 30 weight percent SiO2, 28.4 weight percent A1203, and 11.2 tion are the borosilicate glasses well known to the art, weight percent MgO. The glass-ceramic sealing glass and they are disclosed in “Technical Glassess” by M. P. composition was applied in a bead form and heat was Volf, pages 129 to 153, published by Sir Osaac Pitman applied by means of a gas-oxygen torch. The glass-ceramic and Sons, Ltd., London, and in United States Patent No. crystallized rapidly in the oxygen-gas ?ame with the 1,304,623. Exemplary of borosilicate glasses listed in the blue reducing atmosphere of the inner ?ame cone being above references are the borosilicate glasses of the broad utilized during the sealing stage. The product appeared compositional range ‘comprising 70 to 90 weight percent to be free of strain and the glass-ceramic appeared to SiO2, 5 to 20 weight percent B203, 1 to 6 weight per effectively wet the alloy. cent Al2O3, and 1 to 4 weight percent Na2O. Exemplary EXAMPLE 8 of speci?c borosilicate glasses disclosed within the in 40 stant cited references are the borosilicate glasses con The procedure described in Example 7 was followed in sisting of 80.6 weight percent SiO2, 13.0 weight percent this example with the additional step that Kovar metal B203, 2.2 weight percent A1203, 4.1 weight percent NazO, tubes were sealed to borosilicate glasses. The commer and 0.05 weight percent Fe2O3; a glass consisting of cially-available borosilicate glass used in the sealing proc 80.9 weight percent SiO2, 12.9 weight percent B203, 1.8 ess consists of 80.6 weight percent SiO2, 13.0 Weight per weight percent A1203, and 4.4 weight percent NaZO; and cent B2O3, 2.2 weight percent A1203, and 4.1 weight per a borosilicate glass consisting of 80.0 weight percent cent NazO. The thermally crystallizable sealing glass was SiO2, 11.9 weight percent B203, 2.17 weight percent applied in a beaded form to the metal alloy and the boro A1203, 4.2 weight percent NaZO, and 0.6 weight percent silicate glass then was applied to the bead. Crystallization K20, and the like. was rapid and achieved via a gas-oxygen ?ame. The ?nal The commercially-available metals and alloys that are product appeared to be strain free, and the seal was sur sealed to the glass compositions of the instant invention prisingly strong. include molybdenum, tungsten, nickel, platinum, and EXAMPLE 9 stainless steel, and the like; and the alloys comprising nickel, cobalt, iron, manganese, tungsten, and the like. A piece of molybdenum wire 0.010 inch thick was inti Thesev alloys include the alloy “Kovar” which consists of mately fused to a glass-ceramic composition consisting 29 percent nickel, 17 percent cobalt, 0.3 percent man of 50.4 weight percent SiOZ, 28.4 Weight percent A1203, ganese, and the balance iron; Sylvania No. 4 alloy con 11.2 weight percent MgO, and 10.0 Weight percent ZrO2. The glass-ceramic seal was e?ected employing a gas-oxy sisting of 42 percent nickel, 5.5 percent chromium, and gen oxidizing ?ame, and the crystallized seal produced the balance iron; and the alloy sold under the trade name 60 “Fernico” consisting of 54 percent iron, 28 percent nickel, was good and vacuum tight. and 18 percent ‘cobalt, and the like. EXAMPLE 10 In a typical sealing or joining operation, the glass ceramic composition is usually applied by beading or by A piece of molybdenum rod about one-eighth inch thick was intimately fused to a glass-ceramic composition con ?owing or brushing a slurry comprising ‘?nely divided 65 glass particles in a suitable organic vehicle or carrier sisting of 3.6 weight percent TiO2, 69.7 weight percent onto one or both of the surfaces to be sealed. The slurry SiOZ, 16.8 weight percent A1203, 7.2 weight percent MgO, composition, which is approximately the consistency of and 2.7 weight percent LizO, which composition was in putty, consists of, for example, the powdered or particles bead form with an oxidizing gas-oxygen ?ame. The result of the glass-ceramic nitrocellulose dissolved in amyl ing seal was good and vacuum tight. acetate with a concentration of about 1 to 3% nitro cellulose in said amylacetate. Other acceptable organic EXAMPLE 11 binders may be employed provided they will readily burn The procedure of Example 9 and Example 10 were re off and volatize during the heating procedure of the peated in the present example with the additional step glass-metal or glass-glass assembly. In addition, the or that a borosilicate glass consisting of 80.6 Weight percent 3,473,999 5 6 SiO2, 13.0 weight percent B203, 2.2 weight percent A1203, ceramic or glass-metal seals of the subject invention can and 4.1 weight percent NaZO was applied to the beaded be e?’ected by means of a gas-oxygen ?ame or a suitable thermally crystallizable glass, or glass-ceramic, that was hydrogen ?ame, and the seal formation employed herein ?rst applied to the metal. The heat treating process was as does not require a multi-step procedure of heating in ovens above described, and a very good thermally crystallized or mu?le furnaces at carefully controlled and regulated seal resulted. temperatures. The method is quick and simple and re quires only such equipment as is available to any glass EXAMPLE 12 blower. The sealed joints formed by utilizing the present A molybdenum sheet was dipped into a crucible of process are strong and result from the excellent wetting molten glass of the thermally crystallizable glass com and bonding power of the glass-ceramic and from the su?i position set forth in Example 9, after the molybdenum had ciently close, apparently effective, expansion coe?icients been oxidized, and the process produced a good coating between the crystallized glass-ceramic and the glasses and without cracking. various metals. Moreover, glass-to-metal seals are di?icult EXAMPLE 13 to make in the present state of the art, and this invention 15 provides a useful method of making such seals. In the A glass-to-metal seal was e?ected by employing a fabrication of objects of both clear and opaque parts, the thermally crystallizable glass composition consisting of 10 delineation between the clear and opaque is sharp. weight percent ZIOZ, 50.4 weight percent S102, 28.4 The glass-ceramic sealing glass compositions of the weight percent A1203, and 11.2 weight percent MgO, present invention can be used to fabricate items of com— which composition was intimately sealed to a piece of 20 merce and science. For example, the glass-ceramics can tungsten. The metal was thoroughly cleaned and degassed be used to decorate borosilicate glass such as scienti?c by ?ame-treating the metal before the thermally crystal laboratory glassware with white background graduations lizable, glass-ceramic was applied. A gas-oxygen ?ame or for a white background in thermometers. The sealing was used, and it was adjusted to give a highly oxidizing glasses can also be used to seal lead-in conductors made of temperature. The glass-ceramic readily crystallized, pro metals and alloys in the electronic industries such as duced a good seal, and was vacuum tight. metal lead-in diodes, for sealing metal contacts or ter EXAMPLE 14 minals in glass tubes, as a sealing glass between television faceplates and funnels and the like. The procedure employed in Example 13 was followed I claim: in the present example, except that the glass-ceramic con 1. A composite article of manufacture comprising two sisted of 12 weight percent ZrOz, 49.3 weight percent metal surfaces intimately bonded together by an inter SiOZ, 27.7 weight percent A1203, and 11.0 weight per mediate layer of a glass-ceramic bonding composition cent MgO. The glass-ceramic crystallized and produced a wherein said bonding composition consists essentially of good seal which was vacuum tight. - 40 to 60 weight percent SiO2, 16 to 32 Weight percent EXAMPLE 15 35 A1203, 6-12 weight percent MgO, 0 to 20 weight per cent ZrOz, 0 to 5 weight percent TiOZ, and 0 to 3 weight The procedure employed in Example 13 was followed in percent Li2O. the present example, except that the thermally crystalliz 2. A composite article of manufacture comprising a ‘able, glass-ceramic consisted of 3.6 weight percent TiOg, metal surface intimately bonded to a layer of a glass~ 69.7 weight percent SiO2, 16.8 weight percent A1203, 7.2 40 ceramic bonding composition consisting essentially of 40 weight percent MgO, and 2.7 weight percent LizO. All the to 70 weight percent S102, 15 to 35 weight percent A1203, techniques were as above described, and the glass-ceramic 5 to 15 weight percent MgO, 0 to 20 weight percent produced a very good seal. ZrO2, 0 to 5 weight percent TiO2, and 0 to 3 weight per EXAMPLE 16 cent LiZO. 45 3. A composite article, according to claim 2, wherein The procedure employed in Example 8 was repeated in said bonding composition consists of 5 weight percent the present example, except that a ?ne platinum wire was ZIO2, 53 weight percent SiOZ, '30 weight percent A1203, sealed to the alloy. and 12 weight percent MgO. EXAMPLE 17 4. A composite article, according to claim 2, wherein A composite article of manufacture consisting of both said bonding compositon consists of 7 to 8 weight percent clear and opaque parts was fabricated by intimately seal ZrO2, 51 to 52 weight percent SiO2, 29' to 30 weight ing a thermally crystallizable, glass-ceramic composition percent A1203, and 11 to 12 weight percent MgO. consisting of 10 weight percent ZI'Og, 50.4 weight per 5. A composite article, according to claim 2, wherein cent S102, 28.4 weight percent A1203, and 11.2 weight said bonding compositon consists of 10 to 12 weight per percent MgO to a commercially-available piece of 55 cent ZrOz, 49 to 51 weight percent SiO2, 27 to 29‘ Weight “Kimax” borosilicate tubing consisting of 80.6 weight percent A1203, and 11 to 12 weight percent MgO. percent SiOZ, 13.0 weight percent B203, 2.2 weight percent 6. A composite article, according to claim 2, wherein A1203, and 4.1 weight percent Nazo to produce a white said bonding composition consists of 3 to 4 weight percent background in the tube. The thermally crystallizable, TiOZ, 69 to 70 weight percent SiOg, 16 to 17 weight per glass-ceramic was applied by means of a gas-oxygen cent Al2O3, 7 to 8 weight percent MgO, and 2 to 3 weight ?ame, and there was good wetting and bonding action. percent LizO. Seals effected in this manner with “Kimax” or “Pyrex” 7. An article of manufacture comprising at least one borosilicate glass appear to be strain free. borosilicate glass surface intimately bonded to another Generally, the terms “metals,” “devitritication” and surface by a glass-ceramic composition consisting essen “crystallization,” when used herein may be de?ned as fol 65 tially of 40 to 60 weight percent SiOZ, 16 to 32 weight lows: The term “metals” as used herein includes metals, percent A1203, 6-12 weight percent MgO, 0 to 20 weight metallic alloys, metallic compounds and the like. The percent ZrOz, O to 5 weight percent TiOZ, and 0 to 3 terms “devitri?cation” or “crystallization” when used here weight percent LiZO. in are used in the conventional art sense wherein at least 8. An article, according to claim 7, wherein said boro a part of the glass-ceramic is converted to a crystalline 70 silicate glass surface is bonded to a metal surface. phase and wherein the ?nal properties are determined by 9. An article of manufacture comprising at least one the crystalline phase. borosilicate glass surface intimately bonded to a glass The above disclosure and examples demonstrate the un ceramic composition consisting essentially of 40 to 70 obvious and unexpected results that can be obtained with weight percent SiO2, 15 to 35 weight percent A1203, 5 in the mode and manner of the present invention. Glass 75 to 15 weight percent MgO, 0 to 20 Weight percent ZrO2, 3,473,999 7 8 0 to 5 weight percent TiOz, and O to 3 weight percent 5 weight percent TiO2, and 0 to 3 weight percent Li2O to Li2O. the metal part surface to be bonded, heating said crystal 10. A composite article, according to claim 9, wherein lizable sealing glass to a temperature at least as high as said bonding composition consists of 5 weight percent its melting temperature to e?ect crystallization of said ZrO2, 53 weight percent SiO2, 30 weight percent A1203, sealing glass when contacted with the metal part surface and 12 weight percent MgO. to be bonded and cooling the thus-formed composite 11. A composite article, according to claim 9, where bonded article. ~ in said bonding composition consists of 7 to 8 weight 16. A method for producing an article of manufacture percent ZrO2, 51 to 52 weight percent SiOg, 29 to 30 consisting of both clear and opaque parts wherein said Weight percent A1203, and 11 to 12 weight percent MgO. 10 method comprises intimately bonding a thermally crystal 12. A composite article, according to claim 9, wherein lizable sealing glass composition consisting of 40 to 60 said bonding composition consists of 10 to 12 weight weight percent SiO2, 16 to 32 weight percent A1203, 6-12 percent ZrO2, 49 to 51 weight percent SiO2, 27 to 29 weight percent MgO, O to 20 weight percent ZrO2, 0 to 5 weight percent A1203, and 11 to 12 weight percent MgO. weight percent T102, and 0 to 3 weight percent Li2O to a 13. A composite article, according to claim 9, wherein 15 borosilicate preformed body by heating said sealing glass said bonding composition consists of 3 to 4 weight percent to a temperautre at least as high as its melting tempera TiO2, 69 to 70 weight percent SiO2, 16 to 17 weight per ture to e?ect bonding and crystallization of said sealing cent Al2O3, 7 to 8 Weight percent MgO, and 2 to 3 weight glass to produce said article. percent H20. 17. A method for producing ‘an article of manufacture 14. A method of fabricating a composite bonded 20 consisting of both clear and opaque parts wherein said article of manufacture having at least one metal part method comprises intimately bonding a thermally crystal wherein said method comprises intimately bonding said lizable sealing glass composition consisting of 40 to 70 metal to another surface by applying a thermally crystal weight percent SiO2, 15 to 35 weight percent A1203, 5 to lizable sealing glass composition consisting of 40 to 70 15 weight percent MgO, 0 to 20 weight percent ZrO2, weight percent SiO2, 16 to 32 weight percent A1203, 6-12 0 to 5 weight percent TiO2, and 0 to 3 weight percent weight percent MgO, 0 to 20 weight percent ZrO2, 0 to Li2O to a borosilicate preformed body by heating said 5 weight percent TiO2, and 0 to 3 weight percent Li2O to sealing glass to a temperature at least as high as its melt at least one of the surfaces to be bonded, heating said ing temperautre to effect bonding and crystallization of sealing glass to a temperature at least as high as its melt said sealing glass to produce said article. ing temperature of effect cr/stallization of said sealing 30 glass when contacted with the surfaces to be bonded and References Cited cooling the thus-formed composite bonded article. UNITED STATES PATENTS 15. A method of fabricating a composite bonded article of manufacture having at least one metal part 2,227,770 1/1941 Ungewiss ______161—l93 bonded to a glass-ceramic material, wherein said method 35 ROBERT F. BURNETT, Primary Examiner comprises intimately bonding said metal part to said glass ceramic material by applying a thermally crystallizable WILLIAM J. VAN BALEN, Assistant Examiner sealing glass composition consisting of 40 to 70 weight percent SiO2, 15 to 35 weight percent A1203, 5 to 15 US. Cl. X.R. weight percent MgO, O to 20 weight percent ZrO2, 0 to 40 65-—59, 33; 106-52, 62, 39; 161——196; 287—189.365