US2885838A

US2885838A - Working of titanium

Info

Publication number: US2885838A
Application number: US583624A
Authority: US
Inventors: Douglas E Waite; Royden C Rinker
Original assignee: Armour and Co
Current assignee: Armour and Co
Priority date: 1956-05-09
Filing date: 1956-05-09
Publication date: 1959-05-12
Anticipated expiration: 1976-05-12

Description

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United States Patent 2,885,838 WORKING 0F TITANIUM Douglas E. Waite and Royden C. Rinker, Alliance, Ohio, assiguors to Armour and Company, Chicago, Ill., a corporation of Illinois No Drawing. Application May 9, 1956 Serial No. 583,624

15 Claims. (Cl. 51-281) This invention-relates to an improvement in the working of titanium metal. In one of its aspects, this invention relates to an improvement in .the abrading of titanium metal and its alloys. In another of its aspects, this invention relates to a method for increasing the working life of an abrasive article when used for abrading titanium and its alloys.

In spite of its wide occurrence, titanium has not been used as a structural metal until very recently, principally because of the difficulty of extracting it from its ores. Although titanium has many desirable properties for certain uses, the metal was not commercially available until 1948 and then only in small quantities at high prices.

During 1954, titanium metal production was expanded at a phenomenal rate, despite continuing high prices.

Owing to what must still be considered limited supply, the present applications of titanium are principally for the military, particularly in jet aircraft, although active preliminary investigations are being made in the automotive and commercial aircraft industries of the applicability of titanium in products for civilian use. The uses of titanium and its alloys are a result of a unique combination of properties, namely, light weight, high strength, and good corrosion resistance. At intermediate temperatures, titanium offers weight savings over both alloy steel and alloy aluminum.

Manufacturers of both airframes and aircraft power plants believe titanium alloys will find expanded use in compounds exposed to temperatures as high as 450 C. A few of the items being considered by the airframe producers are skin, fire-walls, landing gear components, hydraulic tubing, exhaust shrouds, oil and fuel tanks, nacelle structures, fasteners, and engine-supports. In gas turbine power plants, compressor discs, compressor blades, compressor housings, retaining blades, retaining rings and fasteners are being fabricated. Other applications of the favorable strength-weight ratio are found where power loss through momentum is involved. Reciprocating equipment, steam turbines, gas turbines, textile machinery, and Diesel engines are fields where titanium metal will find application.

Because of its excellent corrosion resistance, titanium can be applied in the chemical and allied industries, in basic equipment such as autoclaves, heat exchangers, agitators, lined tanks, and the like.

It will be noted that all of the aforementioned uses require that the metal or its alloys be worked and machined in one way or another. Unfortunately, the physical properties of titanium give rise to special problems in machining and related operations. First of all, the metal and its alloys seize and gall upon other metals and hard substances. This is believed to be caused by a tendency for titanium to dissolve or specifically adhere to hard steel and carbide cutting tools and to abrasives such as aluminum oxide, silicon carbide and other common abrasive substances] This is illustrated by the fact that it is possible to mark glass with moistened titanium. Further, it work-hardens rapidly and glazes when light cuts are at- Ice to improvements in the grinding of titanium metal andits alloys. Grinding is essentially an abrading operation achieved by means of abrasive grits in the form of wheels, belts, discs, and the like. The fundamental difiiculties in titanium grinding are the high mutual solubility of titanium in most other metals and refractories or abrasives at elevated temperatures, and the very high temperatures occurring in chip-forming processes. The individual grinding grits are subjected to a combination of high temperature and the severe solution action of titanium. This results in direct attrition and dulling of the abrasive grits by dissolving, or in solution-bonding of titanium to the abrasive grits, causing capping and resultant fracture of the grits. In accordance with the present invention, we have discovered that when certain chemical compositions, which will be more fully described hereinafter, are employed in working titanium metal and its alloys, the aforementioned difficulty can be substantially diminished with considerable lengthening of tool and abrasive article life.

It is, therefore, a general object of the present invention to provide an improvement in the working of titanium metal and its alloys.

It is another object of this invention to provide an improvement in the grinding or abrading of titanium metal and its alloys.

Still another object of the present invention is to pro-- vide a method for increasing the working life of an abrasive article or cutting tool when used for abrading or machining titanium metal and its alloys.

Further and additional objects of the present invention. will become apparent as the specification proceeds.

Broadly, our invention involves working titanium metal or alloy in the presence of a composition consisting of a hydrocarbon or glyceride oil containing between about 25 and 45 weight percent of a chemically combined halogen, such as chlorine, bromine, fiuorine, or iodine. For economic reasons, the preferred halogen is chlorine. These chemicals are not new per se, and can be readily prepared by reacting the halogen with the basic oil in the presence of a catalyst or ultraviolet light with heating when necessary. For example, one preferred composition is prepared by bubbling chlorine gas through tallow in the presence of ultraviolet light at a temperature of about -150 C. until the desired weight percentage of chlorine has been absorbed. Although for practical reasons, it may be desirable to strip the hydrochloric acid formed in the reaction from the resulting oil, from a functional standpoint as respects its use during the working operation, this is not necessary. In fact, in some instances,

the presence of the acid actually promotes the effectiveness present invention.' Hydrocarbon oils such as minerall oil, parafiin oil and the like halogenated to about 25 toz45 Weight percent of halogen can also be employed eifectively.

In practising our invention, the halogenated oils can be applied either to the work itself or to the tool or abrasive article. Generally, it is desirable to heat the oil. so that it is in a fiowable state. The oil is employed in. its full concentration rather than in a diluted or cutback form, and can be continuously circulated during the working operation. It is also possible to employ these halogenated oils in the form of sticks or bars which when applied to the work or abrasive article are spread out. Replenishment of the chemical as used is, of course, required,

We are unable to explain with certainty how or why these halogenated oils function, and do not want to be bound by any particular theory of operation. It is believed that there is a controlled release of chlorine gas which reacts with the titanium metal to form a halide which obviates or diminishes considerably the solutionbonding effect of the titanium metal on the refractory abrasive grit or metallic cutting tool.

Although chlorinated hydrocarbons such as carbon tetrachloride and other low molecular weight halogenated compounds have been employed as grinding aids. These compounds are themselves highly toxic and give ofi even more highly toxic pyrolysis products. Such is not the case with the lubricants of the present invention. Further, other previous lubricant compositions contain very small quantities of halogen and are used as dispersions in water requiring much more costly waterproof abrasive articles. Employing the lubricants of the present invention, non-waterproof abrasives can be used with excellent results.

The improvements of operation achieved in accordance with our invention are quite outstanding. For example, the working life of abrasive belts when used for abrading titanium metal and its alloys have been increased from at least 50 to 3,000 percent. Also, there has been a substantial reduction in the micro inch finish of. the abraded metal or alloy.

Our invention can be further understood with reference to the following examples:

Example! A series of comparative tests employing a number of conventional grinding aids as well as a halogenated oil of the present invention were made by abrading a bar of commercially pure titanium metal /s x 4" x 16" on a platen grinder at 1800 surface feet per minute for a period of two minutes with waterproof silicon carbide cloth belts 4" x 96 /2" having a grit size of No. 120. The grinding aids were applied directly to the metal and the amount of metal abraded during the two minute period was measured by weight difference.

Employing a percent aqueous solution of sodium nitrite, 2.73 grams of titanium metal was abraded in the two minute period.

Employing a commercial grinding aid comprising a soluble oil containing sodium nitrite and nitrate, as a water suspension containing 1 part of oil in 100 parts of water, 4.73 grams of titanium metal was abraded in the two minute period.

Employing a commercial grinding aid comprising a mineral oil containing between 1 and 2 percent sulfur and. between 2 and 3 percent of chlorine, 8.57 grams of titanium metal was abraded in the two minute period.

Employing a commercial grinding aid comprising a soluble oil containing about 2 /2 percent sulfur, as a water suspension containing 1 part of oil in 25 parts of water, 6.45 grams of titanium metal was abraded in the two minute period.

Employing a. commercial grinding aid comprising a soluble oil sold under the trade name Staysoll 77, as a water suspension containing 1 part of' oil in. 16 parts ofiwater, 4.55 grams of titanium metal was abraded in the two minute period.

Employing as a grinding aid a product of the present invention comprising a mineral oil containing between about 25 and 45 weight percent of combined chlorine, 14.25 grams of titanium metal was abraded in the two minute period.

Example II A series of tests was made abrading commercially pure titanium metal as in Example I, using abrasive belts of No. 36 grit silicon carbide on a backstand with an durometer serrated contact wheel. The grinding aids were applied directly to the metal and the amount of metal abraded during a 15 minute period was measured by weight difference.

When no lubricant was employed a total of 45 grams of metal was abraded during the 15 minute period.

When employing the best of the commercially available grinding aids, which was a mineral oil containing between about 1 and 2 percent sulfur and between about 2 and 3 percent chlorine, 56 grams of titanium metal was abraded during the 15 minute-period.

When employing a product of the present invention comprising a mineral oil containing between about 25 and 45 weight percent of combined chlorine, 92 grams of titanium metal was abraded during the 15 minute period.

Example III In an actual commercial plant operation propeller blades of a titanium alloy were abraded with No. aluminum oxide grit belts having brushed thereon at room temperature a mineral oil containing between about 25 and 45 weight percent of combined chlorine as' a grinding aid. The number of propeller blades that could be abraded employing one belt was 3V2 times greater than when a tallow stick was employed as a grinding aid.

Example IV In another commercial plant operation compressor blades of a titanium alloy were abraded with No. 120 aluminum oxide grit belts. A mineral oil containing between about 25 and 45 weight percent of combined chlorine at a temperature of about 120 F. was flowed onto the point of contact between the abrasive article and the work being ground. The number of blades that could be abraded employing one belt was 9 times greater than when a conventional petroleum oil was employedas a grinding aid.

Example V In still another commercial plant operation a titanium alloy was drilled with holes 0.225 inch in diameter which were then reamed-employing as a lubricant for the-reaming a mineral oil containing between about 2 5 and 45 weight percent of combined chlorine. This operation resulted in an out-of-round of 0.0001 inch ascompared to an out-of-round of 0.003 when employing a conventional petroleum oil as a lubricant.

It will be appreciated by those skilled in the art that modifications can be madein the procedures and compounds disclosed without departing from the spirit and scope of the invention.

We claim:

1. In a process wherein a metal selected from the group consisting of titanium metal and its alloys are worked, the improvement which comprises working said metal in the presence of a composition consisting of a compound selected from the group consisting of hydrocarbon oils and glyeeride oils containing between about 25 and 45 weight percent of' chemically combined halogen.

2. A proccess according to claim 1 wherein the composition employed is a halogenated mineral oil.

3. A process according to claim 1 wherein the compound employed isa chlorinated mineral oil.

4. A process according to claim 1 wherein the'compound employed is a chlorinated glyceride oil.

5. A process according to claim 1 wherein the compound employed is chlorinated tallow.

6. In a process wherein a metal selected from the group consisting of titanium metal and its alloys are abraded, the improvement which comprises abrading said metal in the presence of a composition consisting of a compound selected from the group consisting of hydrocarbon oils and glyceride oils containing between about 25 and 45 weight percent of chemically combined halogen.

7. A process according to claim 6 wherein the compound employed in a halogenated mineral oil.

8. A process according to claim 6 wherein the compound employed is a chlorinated mineral oil.

9. A process according to claim 6 wherein the compound employed is a chlorinated glyceride oil.

10. A process according to claim 6 wherein the compound employed is chlorinated tallow.

11. A process for increasing the working life of an abrasive article when used in the abrasion of titanium metal and its alloys which comprises applying to the abrasive grits at their point of contact with the metal a composition consisting of a compound selected from the group consisting of hydrocarbon oils and glyceride oils containing between about 25 and 45 weight percent of chemically combined halogen.

12. A process according to claim 11 wherein the abrasive article is an abrasive wheel.

13. A process according to claim 11 wherein the abrasive article is a flexible coated abrasive in the form of a belt.

14. A process for increasing the working life of a coated abrasive belt when used for abrading titanium metal and its alloys which comprises applying to the abrasive grits at their point of contact with the metal a mineral oil containing between about 25 and weight percent of chemically combined chlorine.

15. A process for increasing the working life of a coated abrasive belt when used for abrading titanium metal and its alloys which comprises applying to the grits at their point of contact with the metal tallow containing between about 25 and 45 weight percent of chemically combined chlorine.

References Cited in the file of this patent UNITED STATES PATENTS Churchill et a1 Dec. 12, 1944 Rocchini et a1. Nov. 7, 1950 OTHER REFERENCES

Claims

1. IN A PROCESS WHEREIN A METAL SELECTED FROM THE GROUP CONSISTING OF TITANIUM METAL AND ITS ALLOYS ARE WORKED, THE IMPROVEMENT WHICH COMPRISES WORKING SAID METAL IN THE PRESENCE OF A COMPOSITION CONSISTING OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF HYDROCARBON OILS AND GLYCERIDE OILS CONTAINING BETWEEN ABOUT 25 AND 45 WEIGHT PRECENT OF CHEMICALLY COMBINED HALOGEN.