Metallurgical composition embodying hard metal carbides, and method of making

• US 3,918,138 A
• Filed: 06/20/1973
• Issued: 11/11/1975
• Est. Priority Date: 06/20/1973
• Status: Expired due to Term

• Current Assignee: Alden M. Burghardt, Bela J. Nemeth
• Original Assignee: Alden M. Burghardt, Bela J. Nemeth
• Inventors: Nemeth, Bela J., Burghardt, Alden M.
• Primary Examiner(s): Padgett, Benjamin R.
• Assistant Examiner(s): Hunt, B. H.
• Application Number:
  US05/371,598
• Time in Patent Office: 874 Days
• Field of Search: 75/203,204 29/182.7,182.8
• US Class Current: 75/237
• CPC Class Codes: C22C 29/08 based on tungsten carbide
• CPC Class Codes: H01F 1/34 non-metallic substances, e.g. ferrites
• CPC Class Codes: Y10S 428/928 Magnetic property

Abstract

A hard wear resistant metallurgical composition, particularly a sintered composition, utilizing hard metal carbides in which the composition can readily be formulated so as to be ferromagnetic or non-ferromagnetic. By non-ferromagnetic, hereinafter referred to as non-magnetic, a material is referred to which has magnetic permeability near unity and which is lacking in the ability to become magnetized or to exhibit induced magnetism, namely, a material with 0 oersted coercive force. The composition is, in general, a combination of tungsten, titanium, nickel and carbon, but may comprise other elements including chromium. In making the composition, tungsten carbide (WC) is admixed by milling with nickel (Ni) and titanium (Ti) and sintered. The titanium can react with carbon from the tungsten carbide and the released tungsten can alloy with nickel to form a tough binder. The characteristics of the end product can be tailored by controlling the proportions of the various components of the composition, including adjustment of the amount of titanium added to the mixture. The end product can, in this manner, be made magnetic or nonmagnetic, if desired, without losing the desirable characteristics of strength, hardness and wear resistance.

Claims

1. A METHOD OF MAKING A SINTERED CARBIDE PRODUT WHICH COMPRISES MILLING TOGETHER A MIXTURE COMPRISING A MAJOR PART TUNGSTEN CARBIDE, TITANIUM, ABOUT 10 WEIGHT % NICKEL, COMPACTING THE MILLED MIXTURE, AND SINTERING THE COMPACTED MILLED MIXTURE TO FORM THE PRODUCT, THE SAID TITANIUM BEING ADDED TO THE MIXTURE CALCULATED IN AN AMOUNT TO DECARBURIZE THE TUNGSTEN CARBIDE TO A DEGREE WHICH WILL RELEASE TUNGSTEN TO FORM AN ALLOY WITH THE NICKEL UP TO ABOUT 28 WEIGHT % TUNGSTEN IN THE ALLOY.

2. The method according to claim 1 which includes adding at least a part of the titanium in the form of an alloy of titanium and nickel.

3. The method according to claim 1 which includes adding at least a part of the titanium in the Form of titanium hydride.

4. The method according to claim 1 which includes adding about 1 weight % chromium to the mixture.

5. The method according to claim 1 wherein the titanium charged in the starting composition is such that the calculated ratio W/(W + Ni) in weight % ranges from about 14 to 28 and the composition in non-magnetic.

6. The method of inhibiting grain growth during sintering in a powder metal compact which is formed from hard metal carbides and nickel which comprises adding about 0.05 to about 2.0 weight % Ti to the mixture from which the compact is formed.

7. A sintered cemented carbide product whose composition comprises tungsten carbide, titanium carbide and a binder alloy comprising tungsten-nickel in which the ratio of the tungsten in the binder alloy to the binder alloy is from 2 to 28 per cent by weight.

8. A product according to claim 7 that is non-ferromagnetic and has a ratio of tungsten in the binder alloy to the binder alloy of 15 to 28 per cent by weight.

9. A product according to claim 7 that has ferromagnetic properties and has a ratio of tungsten in the binder alloy to the binder alloy of less than 14 per cent by weight.

10. A product according to claim 8 in which the powders charged in the mixture before sintering are about the following percentages by weight:

Nickel - 3.0 to 25.0 Titanium - .05 to 2.0 Tungsten Carbide - Balance

11. A product according to claim 8 in which the binder alloy further includes chromium.

12. A product according to claim 11 in which the powders are charged in the mixture before sintering in about the following percentages by weight:

Nickel - 3.0 to 25.0 Titanium - .05 to 2.0 Chromium - 0.0 to 2.0 Tungsten Carbide - Balance

13. A product according to claim 10 in which the titanium is supplied in the form of titanium hydride.

14. A product according to claim 10 in which the titanium is supplied in the form of an alloy with at least a portion of the said nickel.

15. A product according to claim 8 in which the binder alloy further includes un-reacted titanium and the calculated ratio of the tungsten in the binder alloy to the binder alloy is from 15 to 28 per cent by weight.