Abstract
The study is devoted to the development and testing of technological principles for the manufacture of solid end mills from ceramics based on a powder composition of α-SiAlON, β-SiAlON, and TiN additives, including spark plasma sintering powder composition, diamond sharpening of sintered ceramic blanks for shaping the cutting part of mills and deposition of anti-friction Si-containing diamond-like carbon (DLC) coatings in the final stage. A rational relationship between the components of the powder composition at spark plasma sintering was established. The influence of optimum temperature, which is the most critical sintering parameter, on ceramic samples’ basic physical and mechanical properties was investigated. DLC coatings’ role in changing the surface properties of ceramics based on SiAlON, such as microrelief, friction coefficient, et cetera, was studied. A comparative analysis of the efficiency of two tool options, such as developed samples of experimental mills made of SiAlON/TiN and commercial samples ceramic mills based on SiAlON, doped with stabilizing additives containing Yb when processing nickel alloys (NiCr20TiAl alloy was used as an example). DLC coatings’ contribution to the quantitative indicators of the durability of ceramic mills and the surface quality of machined products made of nickel alloy is shown.
Highlights
At present, heat-resistant nickel alloys such as Inconel 718 type are widely used to manufacture critical parts operating under high thermal loads
The hardness of sintered ceramic compositions based on SiAlON was determined at a load of 2 kg by the Vickers pyramid indentation method on a QnessQ10A universal microhardness tester manufactured (Qness GmbH, Mammelzen, Germany)
10 cm/s according to the “ball-ceramic disk” scheme to assess the contribution of the coating to the change in the properties of the ceramics based on SiAlON (80% (90α10β) + 20% TiN) surface layer
Summary
Heat-resistant nickel alloys such as Inconel 718 type are widely used to manufacture critical parts operating under high thermal loads. One of the approaches to increasing the wear resistance of one-piece ceramic end mills can be various coatings deposition on their working surfaces based on complex nitrides and diamond-like carbon structures. Using the example of promising Si-containing diamond-like carbon (DLC) coatings to show their effect on the properties of the surface and the surface layer of sintered ceramic samples; to carry out a comparative analysis of the effectiveness of two cutting tool options—developed samples of experimental end mills made of SiAlON/TiN and industrial samples of commercial ceramic mills based on SiAlON, alloyed with stabilizing additives containing Yb; and to establish the contribution of DLC coatings to the quantitative indicators of the resistance of ceramic end mills and the surface quality of workpieces made of nickel alloy (for example, NiCr20TiAl alloy, standard EN 10269) Within the framework of this work, a set of problems was solved, which can be formulated as follows: 1. development and implementation of laboratory technology for the manufacture of solid ceramic end mills from SiAlON ceramics, including spark plasma sintering powder composition and subsequent diamond grinding of sintered ceramic blanks for shaping the cutting part of end mills of the required geometry; 2. the establishment of a rational ratio between the components of the powder composition α-SiAlON, β-SiAlON, and TiN during spark plasma sintering ceramic blanks and the choice of the sintering process optimal temperature, as the most critical parameter of the technological process (expensive stabilizing additives used in industry in the production of SiAlON ceramics were deliberately excluded); 3. using the example of promising Si-containing diamond-like carbon (DLC) coatings to show their effect on the properties of the surface and the surface layer of sintered ceramic samples; to carry out a comparative analysis of the effectiveness of two cutting tool options—developed samples of experimental end mills made of SiAlON/TiN and industrial samples of commercial ceramic mills based on SiAlON, alloyed with stabilizing additives containing Yb; and to establish the contribution of DLC coatings to the quantitative indicators of the resistance of ceramic end mills and the surface quality of workpieces made of nickel alloy (for example, NiCr20TiAl alloy, standard EN 10269)
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