SUBSTITUTION OF COBALT BY NICKEL IN HARD ALLOYS FOR COMPONENTS SUBJECTED TO WEAR.

HARD ALLOYS BASED ON NICKEL WILL BE DEVELOPED. THESE WILL MAINLY BE COMPOSED OF COMPLEX BORIDES AS WEAR COMPONENTS OF THE -TYPE.

BORIDES OF NICKEL ARE ADDED FOR THE -STABILIZATION (M). OF PARTICULAR INTEREST ARE SPECIAL METALS OF THE IVA- AND VA-GROUP OF THE PERIODIC TABLE OF ELEMENTS WHICH TRANSFER INTO COMPLEX J-BORIDE PHASES OF THE NI21M2B6 TYPE.

THE PROPOSED PROGRAMME WILL BE CARRIED OUT IN TWO PHASES, BEGINNING WITH BASIC RESEARCH ON THE CONSTITUTION AND MELTING BEHAVIOUR OF THE TERNARY SYSTEMS NICKEL-BORON-SPECIAL METAL.

THE FIRST PHASE WILL INCLUDE TESTS IN -BORIDE MATRIX MATERIAL, FOR THE QUATERNARY SYSTEM, NICKEL-CHROMIUM-BORON-SPECIAL METAL. THE MELTING OF THE ALLOYS IS PLANNED IN CONCENTRATIONS WHICH ARE VERY CLOSE TO THOSE USED IN PRACTICAL APPLICATIONS. THE PROPERTIES OF THE ALLOYS, SUCH AS MELTING CHARACTERISTICS, COMPOSITION AND CONSTITUTION OF PHASES AND HARDNESS WILL BE DETERMINED.

IN THE SECOND PHASE, THE BASE ALLOYS WHIXH HAVE BEEN DEVELOPED IN THE FIRST STEP OF THE RESEARCH PROGRAMME, WILL BE FURTHER OPTIMIZED. THIS WILL BE DONE ACCORDING TO THE EXPERIENCE OBTAINED IN THE AREA OF THE DEVELOPMENT OF HARD ALLOYS AND THE PRELIMINARY TESTS, BY ADDING SMAL QUANTITESIES OF OTHER ALLOYING ELEMENTS, SUCH AS CARBON, SILICON AND IRON.

BASED ON THOSE RESULTS, SELECTED QUATERNARY ALLOYS WILL BE MELTED UNDER VACUUM CONDITIONS AND ATOMIZED, UNDER PROTECTIVE GAS ATMOSPHERE, TO POWDERS, FOR THERMAL SPRAYING INTO COATINGS. THESE COATINGS WILL BE SUBJECTED TO LABORATORY AND INDUSTRIAL TESTS.

THE RHEINISCH-WESFAELISCHE TECHNICAL HOCHSCHULE OF AACHEN, FRG, (SUM-003-D) WILL BE FULLY ASSOCIATED WITH THIS PROJECT.