The allotropic transformation of polycrystalline cubic boron nitride structures resulting from the thermal effects of pulsed laser ablation

Laser Processing of Hard and Ultra-Hard Materials for Micro-Machining and Surface Engineering Applications

“…Diamond and Boron Nitride are the hardest among materials identified in Table 1 , with hardness in the range of 40–80 GPa for Polycrystalline diamonds (PCD), 59–75 GPa for Chemical vapour deposition (CVD) diamonds, and 28–44 GPa for Polycrystalline Cubic Boron Nitrides (PcBN) [ 6 ]. Hard materials are classified as materials with a hardness greater than 15 GPa, this includes Tungsten Carbide (WC), Titanium Nitride (TiN), Silicon Carbide (SiC), and Titanium Boride (TiB 2 ) [ 7 , 8 ]. The hardness is dependent on grain size and binder composition [ 9 ].…”

“…Polycrystalline composites are sintered from fine powder grains, between 8–25 µm [ 16 ], using ceramic based or metallic binders. Cobalt is the most common binder for PCD and WC [ 8 ]. For PcBN, silicon, metallic, and ceramic compounds, e.g., aluminium (Al) or TiN are used [ 17 ]; Figure 3 .…”

“…Monitoring the sintering parameters and process is important to minimise unwanted phase transformations ([ 18 , 19 ]), e.g., in PCD, there is a risk of graphitic structures [ 20 ], regions of amorphous carbon [ 17 ], and nanoscopic graphite regions in the cobalt regions [ 21 ]. Sintered materials have a dense isotropic structure with no preferential orientation [ 8 ], which is favourable for hardness, wear resistance, and toughness performance. The transgranular structure causes fractures to propagate through grains and not around grains [ 21 ].…”

A new low-feed chip breaking tool and its effect on chip morphology

“…Localised thermal energy is targeted in a focused beam area on the workpiece and the required shape is achieved via a thermo-mechanical removal process. This technique enables the manufacturing of micro geometries in tight tolerances on most difficult to cut materials [9,10] with minimal thermal damage [11,12]. Process by laser shows advantageous surface quality benefits over grinding and electro discharge machining (EDM) as it is a non-contact process with minimal heat affected zones when using short (< 100 ns) pulse durations [13].…”

Enhanced mechanical properties of hBN–ZrO2 composites and their biological activities on Drosophila melanogaster: synthesis and characterization

“…19,20 Owing to the heterostructures and similarity with carbon, h-BN represents elevated thermal resistance and high mechanical strength. [21][22][23][24][25] The surprising performance of h-BN provides a novel material for the production of numerous technological applications. h-BN-based bioceramics with good chemical stability and high oxidation resistance have been used in diverse research areas at a large scale such as metallic and chemical industries and thermal security systems.…”