US3850583A

US3850583A - Sintered metal containing titanium carbide particles and method for making same

Info

Publication number: US3850583A
Application number: US00335709A
Authority: US
Inventors: K Kueny
Original assignee: Sealed Power Corp
Current assignee: Sealed Power Technologies LP; Kodiak Partners Corp
Priority date: 1973-02-26
Filing date: 1973-02-26
Publication date: 1974-11-26
Anticipated expiration: 1991-11-26

Abstract

The metal part is comprised of a powdered metal mixture which is briquetted under pressure into a desired shape. The mixture includes about 0.25 to 60 percent by weight ferro titanium powder and about 0.1 to 10 percent by weight carbon with the remainder being substantially iron. The briquette is heat sintered to at least approximately 2000*F forming extremely hard titanium carbide particles measuring greater than 70 on the Rockwell C scale. The size and quantity of the titanium carbide particles vary with the percentage of ferro titanium addition and its mesh size.

Description

[4.51 Nov. 26, 1974 1 SINTEREI) METAL CONTAINING TITANIUM CARBIDE PARTICLES AND METHOD FOR MAKING SAME [75] Inventor: Kenneth E. Kueny, Muskegon,

Mich.

[73} Assignee: Sealed Power Corporation,

Muskegon, Mich.

[22] Filed: Feb. 26, 1973 [21] Appl. No.: 335,709

[52] US. Cl 29/1827, 29/1828, 75/200, 75/203, 75/204, 75/227 [51] Int. Cl 1322f 1/00 [58] Field 011 Search 75/203, 204, 227, 200;

[56] References Cited UNITED STATES PATENTS 1,977,361 10/1934 Taylor et a1. 75/204 2,369,211 2/1945 Clark 75/204 3,167,428 H1966 Globus 75/204 3,591,349 7/1971 Benjamin 29/1827 OTHER PUBLICATIONS Schwarzkopf et a1., Cemented Carbides, The Macmillan Company, 1960, pp. 94 TP770S3.

Primary ExamineF-Benjamin R. P'adgett Assistant Examiner-3. Hunt Attorney, Agent, or Firm-Price, Heneveld, Huizenga & Cooper 5 7 ABSTRACT The metal part is comprised of a powdered metal mixture which is briquetted under pressure into a desired shape. The mixture includes about 0.25 to 60 percent by weight ferro titanium powder and about 0.1 to 10 percent by weight carbon with the remainder being substantially iron. The briquette is heat sintered to at least approximately 2000F forming extremely hard titanium carbide particles measuring greater than 70 on the Rockwell C scale. The size and quantity of the titanium carbide particles vary with the percentage of ferro titanium addition and its mesh size.

18 Claims, No Drawings SINTERED METAL CONTAINING TITANIUM CARBIDE PARTICLES AND METHOD FOR MAKING SAME BACKGROUND OF THE INVENTION This invention relates to metal parts, and more particularly to a heat sintered metal part having extremely high wearability.

Hardened iron parts such as iron castings have been the mainstay for years in a host of apparatus and machinery environments where excessive wear and potential failure occurs not infrequently. Evaluations show frequent loss of hardness in these parts to a detrimental extent. Severe loss of hardness is believed to be caused by excessive superficial heat generated by direct metalto-metal contact of the parts. Such contact is generally caused by lubrication breakdowns occurring in a variety of different environments.

Recently, as a result of continual investigation into ways and means for producing a longer lasting higher wearing metal part at reduced economical expenditures, the production of metal parts by briquetting and sintering powdered metal has shown promise. The economical advantages in utilizing powdered metal parts is significant. However, adequate hardness and wearability have been a constant problem utilizing this method. Adequate wearability has been unobtainable to date in a powdered metal part. Thus, there is a need in this art for a metal part produced by heat sintering powdered metals, the resultant'product of which provides acceptable wearability.

SUMMARY OF THE INVENTION In accordance with the invention, an iron based metal part having exceptional wearability is obtained. The component is made by sintering an iron based powder to which has been added about 0.l to 10.0 percent by weight carbon and about 0.25 to 60 percent by weight ferro titanium. The component contains titanium carbide particles having a hardness of greater than 70 on the Rockwell C scale.

The part is formed by mixing an iron powder and carbon with a ferro titanium powder addition. The mixture is briquetted in a press into a desired shape and then heat sintered to at least approximately 2,000F forming the titanium carbides. A commercial grade ferro titanium containing 70 percent titanium works quite well with the particle size varying from 40 mesh and down to 325 mesh or even smaller. Where desired, the mixture of iron powder, ferro titanium and carbon can contain other alloying elements added to the basic mixture. The addition of these other alloying elements however is not essential to the invention defined herein.

The resultant part provides a metal with extremely improved wearability over anything known within the art. The wearability of the resultant material is on the order of 40-50 times better than the materials currently being used in industry today. The process is both simple and extremely economical compared to present methods utilized in the art.

-DESCRIPTION OF THE PREFERRED EMBODIMENTS Generally speaking, the present invention provides a heat sintered powdered mixture which coacts synergistically to provide a metal part having physical properties exceeding that of presently used metals at significantly reduced costs.

The significant steps utilized are to mix in controlled amounts iron, carbon and ferro titanium powders. The controlled amounts of the mixture by weight is about 0.1 to 10 percent carbon and about 0.25 to 60 percent ferro titanium. The remainder is preferably substantially iron although the presence of other metals is permissible, the significance of which will be described hereinafter. The mixture is pressure compacted (briquetted) into a desired shape and heat sintered to at least approximately 2,000F.

The ferro titanium powder preferably utilized in accordance with the invention is a commercially available grade containing about percent titanium powder with a particle size varying from 40 mesh and down to 325 mesh or less. The ferro titanium powder used melts between approximately 2,000-2,'0l2F and a significant aspect of the process is that in the sintering operation, the ferro titanium actually melts and dissolves some or all of the available carbon in the surrounding matrix to form titanium carbide particles. These titanium carbide particles are extremely hard particles ranging upwardly from 70 on the Rockwell C scale. Generally the range has been between 70-90 on the Rockwell C scale using a micro hardness tester. The resultant formation of these titanium carbide particles forms a very hard wear resistant metal. Extensive testing indicates improved wearability on the order of 40-50 times better than materials currently used in the industry today and far superior to any previously known powdered metal parts. Based on present test results, 1,000 hour test 'will yield less than 0.002 inch wear.

The size and quantity of the titanium carbides vary with the percentage and size of the ferro titanium addition. While the mesh size of the iron powder is not of any particular significance in this regard, standard commercial sizes on the order of 40 mesh and down have proven to work extremely well. Higher mesh sizes however will work.

Turning to the basic mixture itself, a number of tests have been conducted utilizing various amounts by weight of the iron, carbon and ferro titanium powders. These tests are set forth in detail below. Greater ranges than presently tested however should work equally well.

One of the more significant aspects of my invention is the synergistic result of mixing, briquetting and heat sintering the ferro titanium powder with controlled amounts of carbon. While the preferred base is iron, other alloying elements should work equally well although they will change certain of the characteristics of the method and resultant metal part. The use of other alloying elements than iron has a large bearing on many factors not dealt with in detail herein. Two such factors of significant interest are increased costs of the powder itself and increased melting temperatures required depending on the mixture. Elevated temperature requirements, of course. also increase the cost factor exponentially.

Regardless of the alloying element utilized however it is the synergistic result of heat sintering a ferro titanium powder with carbon in the surrounding matrix which produces a most unusual resultant metal a ferro titanium powder with carbon in the surrounding matrix which produces a most unusual resultant metal part over any presently known at comparable economical input.

As little as 0.25 percent by weight ferro titanium powder is believed to be adequate. Due to present costs The ferro titanium addition utilized in samples 1 and 2 had a mesh particle size of 40 down to 325 while that utilized in samples 3-5 had a mesh size of 325 and smaller. The ferro titanium powder utilized is available of commercially available ferro titanium powder, a 5 from Chemalloy Company Inc., Bryn Marr, Pa. 19010 practical limit of 60 percent by weight ferro titanium r r as mm r i l q ality ferro i anium powder powder is imposed due to present competitive aspects p ifying per cent grade and mesh Size. The 09 perof the general industrial community. However, higher Cen Ca bon materials were made from Hoeganaes Anamounts will work in unusual circumstances where cost chorsteel 1000 base iron powder available from H0- is not a factor. Regarding the carbon content, a particu- 10 eganaes Corporation, Riverton New Jersey, while the lar range by weight of about 0.1 to 10 percent is envi- 1.7 percent carbon materials were made from Quebec sioned since lower amounts wont produce enough tita- Atomet 28 base iron powder available from Quebec nium carbide particles and higher amounts present e a Powders having an Outlet in Southfieid, problems in briquetting and other related strength fac- Michigan. The heat sintering cycle for samples l-5 tors of the resultant metal part. were identical to that described previously with regard to example 1.

. EXAMPLE 1 Samples l-5 were tested in an Alpha Model LFW-l As a specific example, a powdered mixture of the fol-' Friction and Wear Testing Machine available from the lowing percentages by weight were thoroughly mixed Dow Corning Company. Various ones of each sample by standard procedures in this art: 5% ferro titanium; were tested against a 4620 C ring having a minimum 0.9% carbon; 2.0% copper; and 92.1% iron. .The mesh hardness of 58-on the Rockwell C scale and a hardensize of the ferro titanium powder was from 40 down to bl ir i h vi a minimum hardness of 55.00 on 325 and the iron powder was from 80 mesh and down. the Rockwell C scale. Each test lasted approximately A commercially available iron powder was used which 23.3 hours subjecting the sample to approximately included the carbon and copper. The mixture was com- 275,000 cycles, the Model LFW-l operating at 197 cypr e y a n nti nal pr n a ylin r ricles per minute. In addition to the testing of samples queue having a diameter of inch and a length of 2 l-S, a test was also conducted using a conventional e The Press Utilized developed PP sample of hardenable iron presently being used today, mately 36 tons per square inch.- for comparative purposes. The hardenable iron sample The briquette WaS heat sintered for 6.0 hours. It was used had a size comparable to that of samples 1 5 and gradually heated from approximately 80F to 2,10 a minimum hardness of 55.0 on the Rockwell C scale in 2 hours and maintained at approximately 2,1000]: for thereby exceeding the overall hardness of the test sam- 3 Period of l hourit was Cooled gradually w ples. The results are tabulated in the following table. to F Over 3 Period of 3 hours- After complete Samples l-S are the five previously referred to samples ing to room temperature, resultant metal P was while sample 6 is the comparative hardenable iron test tested for wearability. Present test indications predict Th wealfi re i i volume 1 i bi facial wear Of less than ll'lCh after test inches times ten to the negative six powen hours which is well within acceptable limits.

The presence of copper in the foregoing example was arbitrary in that the particular commercial grade iron 40 powder included it. The presence of other alloying elesample gfg g x f fig g ments does not affect the overall unique characteristics of the invention as illustrated by the presence of molyb- 1 61 denum in other examples set forth below. Minor impu- 2:; 2 2:3 7 5 -rities such as phosphorous or sulphur also do not affect 2 219.2786 28] 8 5 8355 3 the method or resultant art.

in order that those skill d in the art may have a better 6 368 7 284'0 understanding of some of the ranges of controlled amounts of the present invention, the following sam- The foregoing table indicates a totally unexpected ples were made up in accordance with the invention improved wearability over what is in use today from a and subsequently tested for micro examination. The minimum factor of about 5 to l to as high as 94 to 1. percentages listed are by weight of the powdered mix- The results are submitted as being significant especially ture which was subsequently briquetted in a 36 ton in view of present day art and the heretofore unsuccesspress and heat sintered. The weight given is in grams, ful search for an acceptable powdered metal part. the displacement in milliliters and density in grams per In production, the metal parts made in accordance cubic centimeter. The hardness listed indicates the with the invention would be made during briquetting overall hardness of the sample on the Rockwell B scale very close to their final desired geometry thereby reafter sintering. quiring as little machining as necessary after sintering.

Sample %C %Cu %Mo %FeTi Wt. Vol. Den Hardness Appropriate dies could be made for utilization in the pressing step.

ltshould be appreciated that after sintering, the metal part may be subjected to other standard heat treating practices such as carbo nitriding, flame hardening, induction hardening, salt bath, through hardening, etc.

It is conceivable that certain minor variations from the specific compositions noted may be made within the concept presented. The invention is intended to be limited only by the scope of the appended claims and the reasonable equivalents thereto.

The embodiments of the invention in which an exclusive property or privelege is claimed are defined as follows:

1. The method of forming a metal part comprising the steps of: preparing a mixture of powdered material having about 0.25 to 60 percent by weight ferro titanium and about 0.1 to percent by weight carbon the remainder of said powdered material being substantially iron based powder; compacting said mixture and heat sintering said mixture above the melting temperature of the ferro titanium powder whereby the ferro titanium melts and dissolves available carbon in the surrounding matrix to form titanium carbide particles.

2. The method according to claim 1 wherein said ferro titanium powder prior to heat sintering has a mesh size of 40 or less.

3. The method according to claim 1 wherein said ferro titanium powder prior to heat sintering has a mesh size of 325 or less.

4. The method according to claim 1 wherein said mixture contains carbon in the range of about 0.5 to 1.5 percent by weight and ferro titanium in the range of about L0 to 10 percent by weight.

5. The method according to claim 1 wherein said compacted mixture during sintering is maintained at or above 2,000F for a period of approximately one hour.

6. The method according to claim 1 wherein said compacted mixture is heat sintered to at least 2,100F.

7. The method according to claim 6 wherein said compacted mixture during sintering is maintained at or above 2,l00F for a period of approximately one hour.

8. The method according to claim 1 wherein said compacted mixture is gradually heated to about 2,100F over a period of about 2 hours; maintained at about 2,l00F for a period of about 1 hour; gradually cooled to about 825F over a period of about3 hours and then cooled to ambient temperature.

9. The method according to claim 1 wherein said compacted mixture is heat sintered to at least approximately 2,000F.

10. A metal part comprising titanium carbide particles with a hardness of or more on the Rockwell C scale and formed by the steps of: preparing a mixture of powdered material having about 0.25 to 60 percent by weight ferro titanium and about 0.1 to 10 percent by weight carbon, the remainder of said powdered material being substantially iron based powder; compacting said mixture; and heat sintering said mixture above the melting temperature of the ferro titanium powder whereby the ferro titanium melts and dissolves available carbon in the surrounding matrix to form titanium carbide particles.

1 1. The metal part of claim 10 wherein said ferro titanium powder prior to heat sintering has a mesh size of 40 or less.

12. The metal part according to claim 10 wherein said ferro titanium powder prior to heat sintering has a mesh size of 325 or less. 1

13. The metal part according to claim 10 wherein said mixture contains carbon in the range of about 0.5 to 1.5 percent by weight and ferro titanium in the range of about 1.0 to 10 percent by weight.

14. The metal part according to claim 10 wherein said compacted mixture during sintering is maintained at or above 2,000F. for a period of approximately one hour.

15. The metal part of claim 10 wherein said compacted mixture is gradually heated to about 2,100F. for a period of about one hour; gradually cooled to about 825F. over a period of about three hours and then cooled to ambient temperature.

16. The metal part according to claim 10 wherein said compacted mixture is heat sintered to at least approximately 2,000F.

17. The metal part according to claim 10 wherein said compacted mixture is heat sintered to at least 2,l00F.

18. The metal part according to claim 17 wherein said compacted mixture during sintering is maintained at or above 2,l00F. for a period of approximately 1 hour.

Claims

1. THE METHOD OF FORMING A METAL PART COMPRISING THE STEPS OF: PREPARING A MIXRURE OF POWDERED MATERIAL HAVING ABOUT 0.25 TO 60 PERCENT BY WEIGHT FERRO TITANIUM AND ABOUT 0.1 TO 10 PERCENT BY WEIGHT CARBON THE REMAINDER OF SAID POWDERED MATERIAL BEING SUBSTANTIALLY IRON BASED POWDERED; COMPACTING SAID MIXTURE AND HEATS SINTERING SAID MIXTURE ABOVE THE MELTING TEMPERATURE OF THE FERRO TITANIUM POWDERED WHEREBY THE FERRO TITANIUM MELTS AND DISSOLVES AVAILABLE CARBON IN THE SURROUNDING MARTIX TO FORM TITANIUM CARBIDE PARTICLES.

4. The method according to claim 1 wHerein said mixture contains carbon in the range of about 0.5 to 1.5 percent by weight and ferro titanium in the range of about 1.0 to 10 percent by weight.

5. The method according to claim 1 wherein said compacted mixture during sintering is maintained at or above 2,000*F for a period of approximately one hour.

6. The method according to claim 1 wherein said compacted mixture is heat sintered to at least 2,100*F.

7. The method according to claim 6 wherein said compacted mixture during sintering is maintained at or above 2,100*F for a period of approximately one hour.

8. The method according to claim 1 wherein said compacted mixture is gradually heated to about 2,100*F over a period of about 2 hours; maintained at about 2,100*F for a period of about 1 hour; gradually cooled to about 825*F over a period of about 3 hours and then cooled to ambient temperature.

9. The method according to claim 1 wherein said compacted mixture is heat sintered to at least approximately 2,000*F.

10. A metal part comprising titanium carbide particles with a hardness of 70 or more on the Rockwell C scale and formed by the steps of: preparing a mixture of powdered material having about 0.25 to 60 percent by weight ferro titanium and about 0.1 to 10 percent by weight carbon, the remainder of said powdered material being substantially iron based powder; compacting said mixture; and heat sintering said mixture above the melting temperature of the ferro titanium powder whereby the ferro titanium melts and dissolves available carbon in the surrounding matrix to form titanium carbide particles.

11. The metal part of claim 10 wherein said ferro titanium powder prior to heat sintering has a mesh size of 40 or less.

12. The metal part according to claim 10 wherein said ferro titanium powder prior to heat sintering has a mesh size of 325 or less.

14. The metal part according to claim 10 wherein said compacted mixture during sintering is maintained at or above 2,000*F. for a period of approximately one hour.

15. The metal part of claim 10 wherein said compacted mixture is gradually heated to about 2,100*F. for a period of about one hour; gradually cooled to about 825*F. over a period of about three hours and then cooled to ambient temperature.

16. The metal part according to claim 10 wherein said compacted mixture is heat sintered to at least approximately 2,000*F.

17. The metal part according to claim 10 wherein said compacted mixture is heat sintered to at least 2,100*F.

18. The metal part according to claim 17 wherein said compacted mixture during sintering is maintained at or above 2,100*F. for a period of approximately 1 hour.