US2471079A - Glass sealing alloy - Google Patents

Description

Patented May 24, 1949 GLASS SEALING ALLOY Carl B. Post, Wyomissing, and Warren S. Eberly,

Temple, Pa, assignors to The Carpenter Steel Company, Reading, Pa., a corporation of New Jersey No Drawing. Application August 28, 1947,

Serial No. 771,146

12 Claims.

This invention relates to iron-nickel-columbium alloys.

It is an object of this invention to produce glasssealing alloys of the class hereinafter described.

It is a further object to produce substantially gas-free alloys for glass-sealing purposes.

It is a further object to produce an improvement in glass-to-metal seals by eliminating the evolution of gas at the glass-to-metal interface.

As is well known in the art, iron-nickel alloys show a remarkablerange of expansions, depending upon nickel content. This property of obtaining a given expansion depending upon the nickel content is used to obtain alloys of iron and nickel for efiecting glass-to-metal seals.

, At the present time the 42% and 49% nickel seals find wideapplication in glass-to-metal seals, me glasses "being of the borosilicate and leadbearing types. In making iron-nickel alloys for effecting glass-to-metal seals, the nickel can be chosen to yield the desired expansion and carbon is generally held to .07% maximum, manganese .40 to 1.25%, silicon .25/.50%, phosphorus 02% maximum, sulphur .02% maximum.

In making glass-to-metal seals, the metal and glass are chosen on the basis of metal and glass expansion from the strain point or setting point of the glass. These consideration are well known to those skilled in the art and will not be discussed further here.

The metallic parts to be sealed to the glass are formed into cups, pins, tubes, etc., and then cleaned carefully to remove oil, grease and other extraneous impurities. Following this the parts are then generally given a series of costly firing treatments at temperatures of 1900 F. to 2200 F. in dry or wet hydrogen. This high temperature firing treatment can be used to degas the metallic parts, or to put a proper scale on the metallic parts so that the glass will wet the part during the glass-sealing operation.

Under the best of firing techniques, there is some evolution of gas at the glass-to-metal interface in the resulting glass-to-metal seal. This is evidenced by the dull gray appearance of the glass-metal interface. It has long been apparent to those skilled in the art that what is needed to correct this defect is an alloy which is itself substantially gas-free at the glass-to-metal interface during the glass sealing operation. In this way, the firing technique can be directed entirely to preparing the proper scale on the surface for glass-wetting properties, and the amount of firing for degassing can either be dispensed with, or reducedto a minimum.

2 We have discoveredthat the addition of 0.50 to 2.00 per cent by weight of columbium to certain iron nickel alloys creates new alloys which are substantially gas-free during glass-to-metal sealing operations. The new alloys may be identified as to composition by the following analysis:

Percent by weight Carbon (maximum) 0.07 Manganese 0.50 to 2.00 Silicon 0.25 to 1.00 Nickel 30 to Columbium 0.50 to 2.00

All or substantially all of the balance is iron and incidental impurities. The incidental impurities may be illustrated by sulfur e. g. 0.020 maximum and phosphorus 0.020 maximum. Certain specific ranges of nickel content falling within the above mentioned range of 30 to 60 per cent by weight are for example 40.5 to 42.0 and'47.0 to 50.0 respectively.

Theoretically, the evolution of gas during the glass-to-metal sealing operation at temperatures of 1700 F. to 2000 F. can be ascribed to a chemi cal surface reactionbetween the glass and the Per cent Carbon .062 Manganese .99 Silicon .31 Phosphorus .010 Sulphur .004 Chromium .14 Nickel 41.13

and the balance substantially all iron with the exception of incidental impurities. p

The test used to study the amount of gas evolved at glass-sealing temperatures is as follows: A strip of the metal to be studied is supported on spaced blocks of refractory material resting on the hearthoi a furnace capable of reaching 2000 F. A piece of plate glass is laid on the specimen of metal and the temperature of the electrically heated furnace is then raised Carbon (maximum) and the balanc to known temperatures, in the range 1500 F. to 2000 F. The appearance of the glass-metal interface is examined carefully for gas bubbles after being held at a given temperature for 15 minutes. A gassy-metal will show bubbles at the interface a sixteenthof an'inch-in diameter -at-all-temperatures above '15003F.-". Pure electrolytic copper will show no bubbling at temperatures up to 1900 F.

Using this test, the alloy having the actual analysis shown above when not "degassed by a firing technique shows bubbles of aboutone sixteenth of an inch in diameter "at the iglass-tometal interface, at a temperature-M 1400 'F. to 1700 F. and the bubbles increase-maize at' temperatures up to 2000 F. The same alloy base but containing 25% columbium shows-noimprovement in gas evolution. With a 150% columbium addition to the above base, a marked decrease in the amount of gas evolution takesplaca-and the specimens show no -gas evolution until temcolumbium ad'ditio'n the r'e'sulting alloy is substantially gasifree 'at" temperatures up tol2000 F.

'new a11oy'with columbium as was obtained-in the old alloy without columbium. In general it -is necessary to decrease the nickel content 320% -to 40% by weight for each 1:00"% columbium added to 'maintain 'substantially "the"samexpansion in the alloys'vvith and without tl'ie colur'nbium.

What is 'ciaimedds a 1. An alloy having the Eo'mpOsition Percent-by weight 'andthe balanceironanirincidental impurities.

2.-'An alloylravilig the composition Per cent by weight and the balance iron el'nd i'tiidental impurities.

3 An i alloy 'having -the wempesinon *Per-c'entby weight 007 =Manganese 0.50170 2.00 Silicon '0I25to '1L00 Nickel "47 to75'0 Columbium I50 to 2.00

and the balanceiron and incidental impurities.

4. An alloy-having the icomposition ron d incfd'efital impurities said. alloy biil'g" substantial-melamineat: a glassto-metal interface nur-ing glass' 'se'aling operations at temperatures in the' raiige of 1700 to 5. An alloy having the composition and the balance iron and incidental impurities said alloy being substantially gas-free at a glass- -'to-metal interface during glass sealing operations at temperatures in the range of 1700 F. to

6. An alloy having the composition Per cent by weight "Carbon (maximum) 0.07 'Manganese 0.50 to 2.00 Silicon 0.25 to 1.00 "Nickel 47 to 50 Columbium 0.50 to 2.00

and the balance 'iron andinci'dental impurities saidalloy being substantiallyi gas-,free'lat 'agla'ssto-metal-interface during glass sealing eperationsat temperatures in -the rarig'edf l700 to and the balance -iron' a'n'd incidental "impurities said alloy being substa'ritially'gas 'fre'e"atia'glassto-metal interface duringfglas's "sealing operations at temperatures in 'thfeiafige oI-1'I00F.-'t0 2200 F. without pre-firiii'gi'nhyiirogenat"I900"F. to 2200 F.-to degasify theimtal.

8. An alloy having the c'omposition Percentzby weight 'Car-bon maximum)-. 0L0? Manganese 0.50 to 2.00 Silicon s 0.25 130 71.00

Nickel -'40j5 to-'42 Columbium -i 0.50 to- 2.00

and the balanceir'on and incidental impurities said alloy being substafitially gasfree at a "glassto-metal interface during gl'asssealing' operations at temperaturesin'theTalige 'of1I0 0"F. to 2200F. withoutpre firingin iilYd'iogenhtlQOOF. to 2200" 'F'. to 'deg'as'ify'th'e'metal.

9. An alloy havingthe composition rPer :cent=by weight Carbon (maximum) i i 0.0? 0350 "to 2.00 0:25 "to ch00 Columbium 0.50 to 12.00

and the balance iron "and incidental impurities said alloy being substantiallyggas free'at'a'glassto-metal interface during "gl'ass'"'s'ealing' operations at temperatures -inthe range of"1700"F.to

2200 F. without pre firing in'liydro'gen"at"1900 F. to 2200'F. to degasify the'mtal.

10. A 'glass-to-metal seal'betwe'en aglass and an'alloy said alloy being substantiallygas free at the glass-to-metal interface duringiglass sealingoperations at temperaturesfin 't-hemange of 1700 F. to 2200* Fxa'nd havingthe"composition carbon 0.07 per cent maximum,'inian' anese 0.50 to 2.00 per cent, silicon 0.25-to limper'icentjnickel 30 to per cent, columblum iffimto'200' per cent cent and the balance iron and incidental impurities.

12. A glass-to-metal seal between a glass and an alloy said alloy being substantially gas-free at the glass-to-metal interface during glass sealing operations at temperatures in the range of 1700? F. to 2200 F. and having the composition carbon 15 0.07 per cent maximum, manganese 0.50 to 2.00 per cent, silicon 0.25 to 1.00 per cent, nickel 47 to 50 per cent, columbium 0.50 to 2.00 per cent and the balance iron and incidental impurities.

CARL B. POST. WARREN S. EBERLY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,162,489 Mathies et a1 June 13, 1939 2,239,423 Hull Apr. 22, 1941 2,266,481 Talbot Dec. 16, 1941 FOREIGN PATENTS Number Country Date 679,794 Germany Aug. 15, 1937