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.