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Next generation of superhard non-CRM materials and solutions in tooling

Periodic Reporting for period 3 - Flintstone2020 (Next generation of superhard non-CRM materials and solutions in tooling)

Reporting period: 2019-02-01 to 2020-01-31

Flintstone2020 aims to provide a perspective for the replacement of two important CRMs – tungsten (W) and cobalt (Co) – which are the main constituents for two important classes of hard materials (cemented carbides/WC-Co, and PCD/diamond-Co), by developing innovative alternative solutions for tooling operating under extreme conditions.
The use and manufacture of tools drives human technology and economy ever since. Tools from flintstone, one of the first hard materials used by man, were also among the first trans-regionally traded goods, spreading over hundreds or even thousands of km from their original location – in Europe and many other places in the world. In the last century, the sector of hard materials, and hence tooling, has seen great advances, such as the invention of cemented carbide (a composite mainly consisting of tungsten carbide and cobalt, WC-Co), man-made-diamond and the fully-synthetic hard material cubic boron nitride (cBN) with no analogue in nature.
The tooling that is built on critical and scarce raw materials (CRMs) occupies over 80 percent of the entire global tooling market just in metal cutting area. The CRM-containing tooling is divided into three major material groups: Cemented carbide, polycrystalline diamond and cBN, and tool steels, in the descending order of importance and CRM impact. As a consequence, a huge consumption of tooling leads to significant use of these critical and scarce raw materials, tungsten and cobalt globally.
In this proposed project Flintstone2020, excellent scientific partners, world-leading companies have committed themselves to join forces and know-how in order to develop the next generation of superhard materials and solutions in tooling, which do not rely on CRMs.
In WP1, the major effort for this reporting period was concentrated on continued in-depth experimental analysis of wear mechanisms. This was accompanied by thermodynamic modelling for selected tool-workpiece systems, performed in close cooperation with ISM. Similarly, two test rigs for rock cutting were built and performance tests for both reference cemented carbide and PCD, but also for all newly developed PCD grades were performed and analysed. Wear mechanisms in machining titanium and nickel alloys were also in-depth investigated. Lund, in cooperation with Seco, achieved significant progress in modelling and measurement of thermal phenomena in machining. Extended performance testing program was performed amounting to over 1000 for RP3 and nearly 1900 tests overall.
In WP2, CNRS investigated chemical interaction and phase relations in the binary B-X systems (X = N, P, Si, S, Se) and comprehensively characterized a number of new superhard B-X phases. TUBAF established preparation routines for new binder components based on polymer ceramic precursors, chemical vapour, solid state synthesis and subsequent thermal and/or plasma treatment. A large variety of potential binder systems with different binder phases, hard phases and additives (sintering aids, functional materials) were screened. An upscaled preparation route was established to provide material to be sintered by Element Six for one system so far. Upscalable methods to prepare particularly submicron- or even nanopowders, which can be easily and homogeneously mixed with diamond or cBN powders, even without the use of organic solvents were developed. This will reduce process steps and therefore help to reduce production costs and will be more environmentally friendly as compared to conventional mixing procedures.
In WP3 ISM worked on improvement of binder phase content and composition for HPHT sintering of diamond and cBN based materials. In RP3 eight different ratios of binder components for the superhard materials were investigated: two of them included combining two dissimilar types of binder at the same time. Over forty compositions of cBN-based materials were produced by HPHT sintering. The characterization of obtained materials in terms of phase composition, microstructure and mechanical properties was conducted in close cooperation with Lund. The description of sintering technology of prospective binder candidates was transferred to E6 for further implementation to their production line in WP4. 5 binder systems were upscaled independently of E6 and transferred to Seco for tool making.
In WP4 E6 has developed the upscaled process for the developed materials and delivered samples for WP5. In WP5 tool manufacturing was followed by testing. Tool life modelling approaches were investigated to obtain high accuracy data for Cost to Performance Ratio (CPR) analysis. CPR models have been built and investigated for judgement of different technologies and development scenarios. Detailed CPR analysis was completed for reference cemented carbide, pcBN and three novel non-CRM materials.
In WP6, bifa has created an initial dataset for LCA and eco-efficiency analysis which has been updated according to the progress made. bifa has determined, collected and analysed main and by-products with respect to substitution, viable recovery routes and re-use opportunities, and potential customers of different industries were identified for recycling, recovery, re-use of main and by-products as feasible.
WP7 disseminated the results and concluded with a booklet that presents a project overview.
This project has brought about the following innovations:
• Substantial gain on knowledge, e.g. about hard refractory borides at HPHT conditions, cutting processes in which superhard diamond and cBN tools are utilized, properties of new level superhard functional materials, and the impact of non-CRM tool material composition on the fundamental physical and thermal phenomena in metal and rock cutting
• New experimental methods that enable identification and quantification of chemical related tool material degradation mechanisms observed at the extreme pressure and temperature conditions observed in cutting
• Unified model of tool wear accounting for all chemical, diffusional, oxidation, adhesion, and abrasion tool wear mechanisms
• Discovery of novel hard refractory materials with potential to replace CBN and Diamond, and advanced CBN and diamond-based composites with built-in protection against chemical wear
• Clear understanding of the mechanisms and regimes of diamond- and cBN-containing composites sintering with the use of different binders at high pressure and temperatures during liquid- and solid-state processes will be achieved
• At least 2 superhard non-CRM material systems with superior cost/performance ratio to existing cemented carbide machining/milling solutions, and demonstrated performance of cobalt-free thermally stable PCD in rock cutting (MGT)
• Ecoefficiency assessment for downstream optimisation of products and byproducts and mitigation of the consumption of toxic materials and substitution if possible
• Integration of material data, monetary and environmental key performance indicators in product specification linked to process steps

Furthermore, Flintstone2020 expects to have the following impact:
Pushing the EU to the forefront in the area of sustainable raw materials substitution.
Contribution to the large-scale adoption of the new cost-effective technology in the EU
Availability of new materials with improved performance under extreme conditions