The Influence of Dispersion Time On The Mechanical Properties of Spark Plasma Sintered Carbon Nanotubes Reinforced Nickel-Aluminium Matrix Composites

Nickel (Ni) and aluminium (Al) powders were milled with carbon nanotubes (CNT) by employing the high-speed ball milling approach, and the consolidation was achieved by spark plasma sintering technology (SPS). The microstructural evolution of the milled samples and consolidated samples were examined, and the mechanical properties were investigated. The outcome indicated the agglomeration of CNT within the NiAl matrix, and the CNT dispersions improved with the milling duration. The structural integrity of the CNT was evaluated using the Raman analysis which depicted that the ID/IG ratio decreased from 0.986 to 0.867 as the high-speed ball milling was longer, which also depicts more damage to the CNT. The microhardness of the consolidated composite was enhanced from 287.7 HV-320.4 HV due to better dispersion of CNT within the matrix metal. Furthermore, the predicted tensile strength and yield strength of the composite improved from 4011.9 MPa-4428.8 MPa, and from 5747.9 MPa-6389.3 MPa.

Mechanochemical sulfonation of aromatic compounds using NaHSO4·H2O/P2O5

A series of aromatic sulfonic acids is synthesized by subjecting arenes and NaHSO4·H2O to high-speed ball milling in the presence of P2O5. It is suggested the aromatic sulfonation occurs via in situ generated H2SO4 to give aromatic sulfonic acids. In some cases, formation of diaryl sulfones was observed.

Mechanochemical palladium-catalyzed C(sp2)–H homocoupling of N-arylcarbamates: synthesis of 2,2′-biaryldiamines

The palladium-catalyzed dehydrogenative C(sp2)–H homocoupling of N-arylcarbamates under high-speed ball-milling conditions has been achieved using weakly coordinating directing groups, providing access to a variety of 2,2′-biaryldicarbamates.

Cross-Coupling Biarylation of Nitroaryl Chlorides Through High Speed Ball Milling

Solvent-free reaction using a high-speed ball milling technique has been applied to the classical Ullmann coupling reaction. Cross-coupling biarylation of several nitroaryl chlorides was achieved in good yields when performed in custom-made copper vials through continuous shaking without additional copper or solvent. Cross-coupling products were obtained almost pure and NMR-ready. These reactions were cleaner than solution phase coupling which require longer reaction time in high boiling solvents, and added catalysts as well as lengthy extraction and purification steps. Gram quantities of cross biaryl compounds have been synthesized with larger copper vials, a proof that this method can be used to reduce industrial waste and for sustainability.

Semiconductor Pb2P2S6 and size-dependent band gap energy of its nanoparticles

Microcrystalline Pb2P2S6 powder was synthesized via a traditional melting salt method. The nanostructured Pb2P2S6 powder was further synthesized by a high-speed ball milling technique. The optical properties of the Pb2P2S6 powder show a size-dependence, with the band gap ranging from 2.56 eV to 2.88).