Brico Engineering Limited

Federal-mogul Sintered Products Limited

Paritosh Maulik

Leslie John Farthing

Charles G Purnell

Stephen Mcarthur

A most preferred composition for the mixture, prior to sintering into an article (ideally a valve seat insert), is as follows: 35% hard phase, 65% matrix (excepting incidental impurities), the hard phase component being 2.2% C, 29.1% Cr, 4.9% Co, 5.3% Ni, 20.2% W with the balance being Fe and allowing less than 2% for one or more machinability aids and solid lubricants, and the matrix component being one of a high chrome steel powder (e.g. 18% Cr, 1% Ni, 2.5% Mo, balance Fe), a low alloy steel powder (3% Cu, 1% C, balance Fe; 3% Cr, 0.5% Mo, 1% C, balance Fe; 4% Ni, 1.5% Cu, 0.5% Mo, 1% C, balance Fe; 4% Ni, 2% Cu, 1.4% Mo, 1% C, balance Fe), or a tool steel powder (5% Mo, 6% W, 4% Cr, 2% V, 1% C, balance Fe), or a low-alloy steel powder as above but which issued in conjunction with a copper infiltration process during sintering.

Powder metallurgy composition

The method comprises preparing an iron-based powder mixture, and compressing and sintering the mixture to form the component. Said mixture comprises a first powder which forms 40 to 60 wt % of the mixture and which is an atomised pre-alloy comprising nickel, cobalt and iron, a second powder which forms 30 to 50 wt % of the mixture and essentially consists of iron, a third powder which essentially consists of ferromolybdenum, a fourth powder which essentially consists of graphite, and optionally a fifth powder which consists essentially of ferrotungsten. The component has a composition comprising 5 to 11 wt % of nickel, 5 to 11 wt % of cobalt, 5 to 8 wt % molybdenum, up to 1 wt % tungsten, 0.25 to 0.9 wt % carbon, and a balance which essentially consists of iron.

Method of forming a component by sintering an iron-based powder mixture

Valve seat insert of two layers of same compact density

Sintered materials and a method for their manufacture are described together with products made therefrom, such as piston rings and valve seat inserts for internal combustion engines. The sintered material comprises a porous matrix with a composition lying in the range expressed in wt % of 8 to 12 chromium, 0.5 to 3 molybdenum, up to 1.5 vanadium, 0.2 to 1.5 carbon, other impurities 2 max., up to 1 manganese sulphide, optionally up to 5 molybdenum disulphide, balance iron, the matrix having a uniform dispersion of submicroscopic particles of molybdenum rich carbides which render the material resistant to thermal softening.

Growing community of inventors

Coventry, United Kingdom

Paritosh Maulik