Electron Deficiency but Semiconductive Diamond-like B2CN Originated from Three-Center Bonds

B2CN was one of the synthesized light element compounds, which was expected to be superhard material with metallic character due to its electron deficiency nature. However, in this work we discovered...

Finding the Next Superhard Material through Ensemble Learning

We report an ensemble machine-learning method capable of finding new superhard materials by directly predicting the load-dependent Vickers hardness based only on the chemical composition. A total of 1062 experimentally measured load-dependent Vickers hardness data were extracted from the literature and used to train a supervised machine-learning algorithm utilizing boosting, achieving excellent accuracy (R2 = 0.97). This new model was then tested by synthesizing and measuring the load-dependent hardness of several unreported disilicides as well as analyzing the predicted hardness of several classic superhard materials. The trained ensemble method was then employed to screen for superhard materials by examining more than 66,000 compounds in crystal structure databases, which showed that only 68 known materials surpass the superhard threshold. The hardness model was then combined with our data-driven phase diagram generation tool to expand the limited num1 ber of reported compounds. Eleven ternary borocarbide phase spaces were studied, and more than ten thermodynamically favorable compositions with superhard potential were identified, proving this ensemble model’s ability to find previously unknown superhard materials

Finding the Next Superhard Material through Ensemble Learning

We report an ensemble machine-learning method capable of finding new superhard materials by directly predicting the load-dependent Vickers hardness based only on the chemical composition. A total of 1062 experimentally measured load-dependent Vickers hardness data were extracted from the literature and used to train a supervised machine-learning algorithm utilizing boosting, achieving excellent accuracy (R2 = 0.97). This new model was then tested by synthesizing and measuring the load-dependent hardness of several unreported disilicides as well as analyzing the predicted hardness of several classic superhard materials. The trained ensemble method was then employed to screen for superhard materials by examining more than 66,000 compounds in crystal structure databases, which showed that only 68 known materials surpass the superhard threshold. The hardness model was then combined with our data-driven phase diagram generation tool to expand the limited num1 ber of reported compounds. Eleven ternary borocarbide phase spaces were studied, and more than ten thermodynamically favorable compositions with superhard potential were identified, proving this ensemble model’s ability to find previously unknown superhard materials

Influence of diamond component based on wurtzite boron nitride on wear resistance of cutting tool

The article is devoted to the study of the influence of the diamond component in a composite superhard material based on wurtzite boron nitride on the stability of the tool during turning of hardened steels in the mode of smooth turning and when processing intermittent surfaces. The aim of the work is to study the influence of the content of the diamond component in the composite superhard material based on wurtzite boron nitride on the stability of the tool. Based on the analysis of the main patterns of changes in the coefficient of friction depending on various factors, the evaluation of composites containing diamonds of different dispersion in comparison with other materials of this class. The results of the study of the technical level of composite polycrystalline superhard materials based on wurtzite boron nitride of different composition and determination of the efficiency of their use as a cutting tool in the machining of hardened steels are presented. The intensity of wear of composites in the cutting tool during processing of hardened steels is experimentally determined. It is established that the presence of a diamond component in the composite significantly affects the stability of the tool in the conditions of smooth turning due to heat dissipation in contact with the processed material. In the processing of hardened steels with the presence of shock loads, the phase state of the matrix component of the composite plays a decisive role. The obtained research results make it possible to determine the optimal composition and conditions for obtaining a composite material of the system “boron nitride – diamond”, which provides the most effective application of the cutting tool in practice.

Structural, elastic and electronic properties of new superhard orthorhombic C28

The structural, mechanical and electronic properties of recently reported superhard material C[Formula: see text] are studied by first-principles calculations. The unit cell of C[Formula: see text] is composed of 28 carbon atoms and all sp3 hybridized bonds. From 0 GPa to 100 GPa, C[Formula: see text] satisfies the mechanical stability criteria and the phonon spectrum of C[Formula: see text] has no imaginary frequency, which means that C[Formula: see text] is mechanically and dynamically stable. The results of hardness calculated show that C[Formula: see text] is a potential superhard material with the Vickers hardness of 84.0 GPa. By analyzing the elastic anisotropy, we found that elastic anisotropy of C[Formula: see text] increases with pressure. The calculations of band structure demonstrates that C[Formula: see text] is an indirect bandgap semiconductor with the gap of 4.406 eV. These analyses demonstrate C[Formula: see text] is a superhard semiconductor material.