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Content archived on 2024-04-15

TOUGH TITANIUM BASED CERMETS FOR TOOLS AND WEAR RESISTANT COMPONENTS

Objective

The objectives of this project are: To devise Titanium based cermets with technologically superior properties to replace WC-based hardmetals in various metal-cutting and wear resistant applications To identify the microstructural parameters and mechanisms controlling the properties by developing analytical techniques with high spatial resolution (less than 0.1 micrometre) particularly for the light elements, carbon and nitrogen. To study mechanical property data acquisition techniques for hard materials and define their applicability to cermets. To manufacture and characterize new and improved Ti(C,N) powders and develop commercial techniques for their manufacture. To develop new processing routes and quality control procedures for sintered cermets. To carry out performance tests comparing new compositions with existing tools.
The project sought to study the microstructural mechanisms controlling toughness and strength, thus facilitating the production of titanium based cermet compositions with technologically superior properties. After study, this projectaimed at the manufacturing and characterization of new and improved titanium (carbon, nitrogen) powders.
A pilot plant approach was devised for the manufacture of micrometre sized titanium (carbon, nitrogen) powders with nitrogen to carbon ratios ranging from 0 to 0.43. Also, a method for production of quaternary solid solution carbon-nitride powders was devised. Accuracy and repeatability of analysis methods for nitrogen in both powders and sintered cermets were improved 10 fold. The project work also resulted in the wider availability of European sources of titanium (carbon, nitrogen) powders.
The project manufactured and successfully reproduced microstructural state of the art Japanese cermets with equivalent hardness.
A sintering route was devised in which control of gas atmosphere (nitrogen/methane) led essentially to porosity free sintered bodies by inhibiting nitrogen loss. Also, a method was devised to control the nitrogen to methane ratio during sintering in order to maintain a constant carbon to nitrogen ratio. Sintering conditions were quantified to control grain size and binder phase content. The potential of magnetic measurements, coercivity and saturation for quality control of the microstructures of sintered cermets was established by the project.
Performance tests were conducted to establish cutting conditions on chromium molybdenum steels to enable cermets to be differential in their flank and crater wear response. Cermet composition, binder-phase content, and hard particle phase size were found to be extremely important to cutting performance.
Cermet mechanical properties were tested. Parameters affecting measurement of surface (Palmqvist) toughness were quantified. A test procedure was devised to specify significa nt differences in toughness of cermets assessed by the Palmqvist method.
In characterizing cermet microstructure, the importance of high electron resolution microscopy for elucidated phase size and distribution was demonstrated. Evidence showed that many existing models for microstructural composition are too simple. Most commercial materials were found to contain up to 6 different phase constituents, compared with 3 or 4 claimed in most current patents.
Analysis routines were developed using electron energy loss spectrometry (EELS) for light elements carbon and nitrogen in hard particle phases of cermets.
FOUR COOPERATING BODIES HAVE UNITED IN THIS RESEARCH PROPOSAL BECAUSE THEIR ROLE WOULD BE COMPLEMENTARY, AND BY WORKING TOGETHER THEY WOULD PROVIDE COMPREHENSIVE COVERAGE OF ALL ASPECTS.

- NPL WOULD BE THE CENTRAL RESEARCH FACILITY FOR DEVISING NEW COMPOSITIONS, IDENTIFYING MICROSTRUCTURAL MECHANISMS, CHARACTERISING POWDERS AND MECHANICAL PROPERTIES OF SINTERED MATERIALS AND MEASURING RESISTANCE TO WEAR, OXIDATION AND CORROSION.
- LSM WOULD MANUFACTURE AND CHARACTERISE THE IMPROVED POWDERS AND DEVELOP NEW COMMERCIAL SCALE TECHNIQUES FOR THEIR MANUFACTURE.
- ANDERSON STRATHCLYDE WOULD DEVELOP NEW PROCESSING ROUTES FOR MANUFACTURING SINTERED SAMPLES AND PRODUCTS FROM EXISTING AND EXPERIMENTAL POWDERS, AND DEVELOP APPROPRIATE QUALITY CONTROL PROCEDURES.
- KOMET WOULD PERFORM COUTINUOUS TURNING TESTS ON EN24 TOOL STEEL TO COMPARE PERFORMANCE WITH EXISTING CUTTING TOOLS. LATER TESTING WOULD EXTEND TO INTERRUPTED CUTTING.

CONSIDERABLE ECONOMIC BENEFITS WILL ACCRUE FROM THE POTENTIAL SUPERIORITY OF TI-BASED CERMETS OVER WC-HARDMETALS AT HIGHER CUTTING SPEEDS, FOR FINISH CUTTING OF AEROSPACE MATERIALS, FOR HIGH TEMPERATURE OXIDATION-RESISTANT FORMING TOOLS, FOR CORROSION AND WEAR RESISTANT COMPONENTS AND FOR LOW FRICTION LOSSES IN MECHANICAL SEALS, DIES AND GUIDES ETC.
AS AN EXAMPLE, FOR EEC INDUSTRIES THERE WOULD BE ANNUAL SAVINGS IN MACHINING COSTS OF ABOUT 80 M ECU BY USING TI-BASED TOOLS TO OBTAIN A 50% REDUCTION IN MACHINING TIMES; DOUBLING THE LIFE OF MECHANICAL SEALS COULD SAVE MORE THAN 5 M ECU ANNUALLY. CLEARLY A SOURCE OF RELIABLE SOLID TI-BASED TOOLS WOULD ALSO ELIMINATE MUCH OF THE NEED TO USE COSTLY TI-COATED INDEXIBLE INSERTS. THE RESEARCH IS INNOVATIVE IN THE METHODICAL AND FUNDAMENTAL APPROACH USED TO ACHIEVE THE OBJECTIVES, THE APPLICATION OF ADVANCED ELECTRON AND ANALYTICAL FACILITIES, THE USE OF NEW TECHNIQUES FOR MEASURING TOUGHNESS, STRENGHT AND WEAR PARAMETERS AT ROOM AND HIGH TEMPERATURES, AND THE APPLICATION OF A NEW NPL TECHNIQUE WHICH ENABLES A WIDE RANGE OF POTENTIAL COMPOSITIONS TO BE INVESTIGATED SYSTEMATICALLY, INEXPENSIVELY AND RAPIDLY.

Topic(s)

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Call for proposal

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Coordinator

National Physical Laboratory (NPL)
EU contribution
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Participants (3)