Report

Teaser, summary, work performed and final results

Periodic Reporting for period 2 - Flintstone2020 (Next generation of superhard non-CRM materials and solutions in tooling)

Teaser

The overall aim of this project is 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...

Summary

The overall aim of this project is 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 in the following application areas:
1. Machining ferritic and perlitic materials (steels and irons);
2. Machining austenitic materials (stainless steels and superalloys);
3. Machining titanium alloys and other special materials (composite materials);
4. Machining martensitic materials (hardened steels);
5. Cutting and processing rock and concrete.

The use and manufacture of tools drives human technology and economy ever since. 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.

Work performed

In WP1, the major effort was concentrated on continued in-depth experimental analysis of wear mechanisms, accompanied by thermodynamic modelling for selected tool-workpiece systems, performed in close cooperation with ISM. Wear mechanisms in machining titanium alloys were also in-depth investigated. Performance screening was performed for materials developed in WP3 and those upscaled in WP4. In WP2, CNRS investigated chemical interaction and phase relations in the binary B-X systems and comprehensively characterized a number of new superhard B-X phases. The developed method of ultra-fast mechanochemical synthesis of nanopowders of boron phosphides at ambient pressure is characterized by simplicity of implementation, high efficiency, low cost of the product, and good perspective for large-scale production. 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. TUBAF is working on the improvement of the high-pressure cell design for HPHT sintering for the upscaled manufacture of intermediate sized samples (5-8 mm) for the second testing stage within WP1. ISM continued work on searching of prospective binder phases for cBN-based and diamond-based materials. The characterization of obtained materials in terms of phase composition, microstructure and mechanical properties were conducted with close cooperation with LU. In parallel a thermodynamic analysis of several systems with cBN were analyzed in order to predict possible interaction products. Sever trial experiments were done in order to achieve diamond-based materials on a cemented carbide substrates with a mechanism of infiltration by cobalt and MeN compound. At the same time, the description of sintering technology of prospective binder candidates was transferred to E6 for further implementation to their production line. Element 6 has developed the process and produced 3 PCD systems and 4 PcBN system prototypes, delivered to Lund University in Q4 2018. These parts are currently going through pre-screening tests at LU, to allow for final selection of the 3 most promising systems to produce additional pieces of for Deliverable 5.2 (which will lead to field testing).Information from these runs will provide evidence for Deliverable 4.1, 4.2 and 4.3 (improved carbide life evidence, cost-performance indicators and yield information for potential commercialisation). In WP5 benchmark FE simulation studies were upscaled to 3D oblique machining cases, which were validated experimentally. Temperature data measured in WP1 were applied during the modelling to assure desired accuracy. Impact of cutting edge radius on thermo-mechanical loads on a pcBN cutting tool in machining Inconel 718 was studied. It was found that full simulation array, for 3D case, covering all major tool design parameters is computationally prohibitive and focus was shifted to 2D cases. 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.In WP6, first results of the LCIA have shown that the biggest environmental impacts can be expected within the mining and application phase; the contribution from tool production is rather small. Currently alternative binder systems according to the progress made in the project are investigated for potential REACH or waste issues and CRM properties. In WP7 stakeholder workshops are planned. First one is in Lund, date is 9th and 10th of April On the 4th and 5th of June the 2nd workshop will be held in Freiberg.

Final results

This project will bring 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
• 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 to achieve full environmental traceability and eco-efficiency optimisation in automated productions.

Website & more info

More info: http://flintstone2020.eu.