STUDIES OF THERMAL SHOCK RESISTANCE OF AN ANTI-OXIDATION COATING FOR A MULTI-LAYERED CERAMIC COMPOSITE

The article covers the performance of thermal shock resistance experiments of a ceramic composite with two types of anti-oxidation coatings. A thermal shock burner rig was used to carry out the experiments similar to those expected in a combustor of a turbojet engine. SEM and х-ray diffraction analyses were used to examine the antioxidation coatings. It was deter-mined that the coating based on the refractory compounds possesses high thermal shock resistance when exposed to the fuel gas flow from a burner rig.

Fabrication and properties of Si2N2O ceramics for microwave sintering furnace

The Si2N2O ceramics with low dielectric constant, low thermal diffusivity and high thermal shock resistance were successfully prepared by vacuum sintering. The amorphous Si3N4 was used as raw material with Li2CO3 as sintering additive. The phase, microstructure, oxidized resistance, mechanical and dielectric properties of the Si2N2O ceramics were investigated. XRD analysis showed that the suitable content of Li2CO3 could promote the generation of Si2N2O ceramics. However, the excess or insufficient amount of Li2CO3 additive would cause decomposition of Si2N2O phase. The Li2O volatilized at high temperature leaving highly pure (99.63%) porous Si2N2O ceramics. The flexural strength of the porous Si2N2O ceramics (with ?49.19%of open porosity) was about 30MPa, the residual strength ratio was more than 70% after 1300?C quenching in air. The SiO2 layer formed by oxidization could prevent Si2N2O ceramics from further oxidizing. Therefore, these Si2N2O ceramics will be excellent thermal insulation and wave-transparent materials for high temperature microwave sintering furnace.

Characterization of Li2O-Al2O3-SiO2 glass-ceramics produced from a Brazilian spodumene concentrate

Glass-ceramics in the LAS (Li2O-Al2O3-SiO2) system with high thermal shock resistance were successfully obtained using Brazilian spodumene concentrate as the main raw material (80-70 wt%). Two compositions (Li2O.Al2O3.nSiO2) were produced with n= 2 and 4, near to the stoichiometric compositions of β-eucryptite and β-spodumene. The characteristic temperatures of parent glasses were determined by contact dilatometry, differential scanning calorimetry and heating microscopy. The crystallization mechanism and the effect of the nucleating agent (TiO2.2ZrO2) required to promote volume crystallization in the parent glasses were investigated. Microstructural and structural changes with temperature were also evaluated by optical microscopy and X-ray diffraction. The obtained glass-ceramics presented coefficients of thermal expansion between -0.370x10-6 and 4.501x10-6 °C-1 in the 22 to 700 °C range.

Investigation of High-Velocity Projectile Penetrating Concrete Blocks Reinforced by Layers of High Toughness and Energy Absorption Materials

Recently, the need to protect people and structures against attacks of terrorists are of a high increase. The main objective of this paper is to enhance the concrete resistance against ballistic impact of high velocity projectile by using different combination layers from different materials as reinforcement for concrete and investigate their effect on the penetration depth of projectile and the resulted damage of concrete. The investigation presents the development of a finite element accurate models using AUTODYN 3D. The Lagrangian formulation numerical techniques is used to model the projectile and concrete target. The investigated models are reinforced using different layers combinations of several materials such as ceramics, fiber composite, polymer and metal: (AL2O3 - 99.7% and Kevlar- epoxy, Teflon and aluminum alloy 6061-T6) .Those materials were chosen because of their high thermal shock resistance or their great capability in energy absorption. The main findings showed a significant enhancement in the reduction of penetration depth compared to the concrete resistance without reinforcement, which demonstrate the great performance of the used combinations in the shock wave propagation. Hence from the findings of this work we can say that the concrete reinforced by ceramics or aluminum alloy with fiber composite or polymer can be used for several applications as it represents a successful anti-penetration composite structure.

MANAURITE 900X

MANAURITE 900X is a casting alloy with good creep strength and high thermal shock resistance. This alloy is evolution from Manaurite 900 (Alloy Digest SS-1304, March 2019). This datasheet provides information on composition and physical properties as well as creep. It also includes information on high temperature performance as well as joining. Filing Code: SS-1305. Producer or source: Manoir Industries, Manoir Pîtres.