Abstract: 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.

Abstract: 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.

Abstract: A process for the manufacture of a ferrous-based sintered article containing copper in the range from 12 to 26 weight % is described, the process including the steps of: making a powder mixture having a desired composition, at least a proportion of a total content of iron and copper being provided by an iron powder having copper indivisibly associated therewith for instance being pre-alloyed or diffusion bonded; compacting said powder mixture to form a green compact of an article to be produced and sintering said green compact.

Abstract: 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.

Abstract: A two layer valve seat insert and a method for its manufacture is described. The method comprises the steps of preparing two powder mixtures; a first powder mixture for forming the valve seat face layer; a second powder mixture for forming the valve seat base layer; sequentially introducing a predetermined quantity of each of said first and said second powder mixtures into a powder compacting die and having an interface therebetween substantially perpendicular to the axis of said die; simultaneously compacting said first and said second powder mixtures to form a green compact having two layers and sintering said green compact, wherein at least one of the chemical composition or the physical characteristics of at least one of said first and said second powder mixtures is adjusted so as to result in said valve seat face layer and said valve seat base layer having substantially the same density after compaction.

Abstract: 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.