Effect of boron nitride addition on some properties of aluminosilicate refractories

Conclusions An addition of 10–60 wt.% of boron nitride significantly alters the thermal conductivity, thermal expansion, and the elastic modulus of aluminosilicate refractories.As the boron nitride content is increased from 1–60% the strength of specimens heated in a nitrogen atmosphere with an oxygen content of 0.02% decreases.During cyclic heat treatment in an oxidizing atmosphere between 900 and 20°C additional bonds develop between the particles of the aluminosilicate and the oxygen-free additive. As a result the strength of the specimen increases.The thermal shock resistance of the specimens increases with an increase in the amount of boron nitride addition. Specimens with 40–50% boron nitride addition are in practice insensitive to temperature drops in the range 20–2400°C.Aluminosilicate refractories with the addition of 30–40 wt.% of boron nitride can be used as lining material in high temperature systems with brief nonsteady or cyclic work schedules.Translated from Ogneupory, No. 4, pp. 36–39, April, 1968.     

Three-dimensional analysis of a functionally graded coating/substrate system of finite thickness

The concept of functionally graded material (FGM) is currently actively explored in coating design for the purpose of eliminating the mismatch of thermomechanical properties at the interfaces and thus increasing the resistance of coatings to functional failure. In the present paper, three-dimensional elastic deformation of a functionally graded coating/substrate system of finite thickness subjected to mechanical loading is investigated. A comparative study of FGM versus homogeneous coating is conducted to examine the effect of the coating type on stress and displacement fields in the system.     

Determination of the critical ductile-brittle transition temperature in testing the cracking resistance of steels

Institute of Strength Problems, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Problemy Prochnosti, No. 1, pp. 7–11, January, 1988.     

Performance of functionally graded plates under localised transverse loading

This paper presents a study of the bending of an isotropic functionally graded plate under localised transverse load through a combination of analytical and computational means. The analytical modelling is based on the recently developed three-dimensional elasticity solution, expanded to cover different loading types, whilst the Finite Element model uses graded isoparametric elements. The plate under consideration is assumed to be simply supported, with Young’s and shear moduli varying exponentially through the thickness and the Poisson’s ratio constant. Comparative analysis of stress and displacement fields in functionally graded and homogeneous plates subjected to uniformly distributed and patch loadings is carried out.     

Brittle-to-ductile transition in steels and the critical transition temperature

Specimens of different thickness made of a low-alloy steel were tested to determine fracture toughness under static and impact loading at room and low temperatures. It was found that for the specimen of each thickness there was a specific brittle-to-ductile transition temperature T_psdefined as the upper temperature boundary up to which plane-strain conditions were valid at fracture. The temperature T_ps, as well as the brittleness transition temperature T ₅₀ (determined via the 50% ductile component of the fracture surface), rose with the increase in the thickness B of a specimen. The value of T_pswas found to be in a linear dependence on lgB for both static and impact loading.

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Résumé On a procédé à l'essai d'éprouvettes de différentes épaisseurs réalisées en acier faiblement allié en vue de déterminer la ténacité à la rupture sous charge statique et d'impact à température ambiante et à basse température. On a trouvé que pour les éprouvettes correspondantes à chaque épaisseur, il existait une température de transition spécifique ductile-fragile T_ps, définie comme la limite supérieure de température sous laquelle les conditions d'état plan de déformation sont atteintes à la rupture. La température T_psainsi que la température de transition de fragilité T₅₀, correspondant à une surface de rupture présentant 50% de ductilité, se relèvent avec un accroissement de l'épaisseur B de l'éprouvette. La valeur de T_ps a été trouvée en dépendance linéaire du lgB à la fois en contrainte statique et en contrainte d'impact.