k. kolahgar azari

One of the main challenges in advanced industries in the field of future technologies is the existence of materials that can maintain their integrity at temperatures above 2000 degrees Celsius. Ultra-high temperature ceramics (UHTCs) are among the attractive options for meeting this industrial need. Resistance to oxidation and linear and mass erosion is one of the most important and influential properties of these high-temperature ceramics. Hf and Zr diborides are the most important materials among high-temperature ceramics for these components, showing the best resistance to oxidation up to a temperature of 1500 degrees Celsius. Especially ZrB2 has received more attention due to its low density and low cost. However, two important factors hinder its application: firstly, it contains a high amount of boron. Boron oxides quickly vaporize at temperatures above 1200 degrees Celsius, resulting in severe material loss due to hot gases. Secondly, due to its brittleness and low thermal shock resistance, it is prone to sudden fracture. In order to reduce the evaporation of boron oxides and improve the erosion resistance of ZrB2, significant attention has been given to adding silicides (such as SiC, MoSi2, etc.) and carbides (such as ZrC) to ZrB2 to form multiphase ceramics. On the other hand, relatively little attention has been paid to the development of single-phase ceramics with multiple elements. Although ZrC is less prone to evaporation at high temperatures due to the absence of boron, it has lower oxidation resistance compared to diborides (such as ZrB2) and is weaker. This makes it less suitable for anti-erosion applications. The mentioned factors indicate that high-temperature ceramics are limited in their application in environments with very high temperatures, and new single-phase ceramic materials with lower evaporation rates and better oxidation resistance need to be developed. This research focuses on recent studies on increasing the oxidation resistance of ZrB2 composites in detail.

Hybrid composites are a kind of composite produced with two or more different reinforce. One of the production technologies is using metal-fiber layers in a hybrid composite. In the present study, for the production of Hybrid composite, samples were prepared from glass fiber (S glass), aluminum alloy sheet (2024), and epoxy resin (F grade) using Resin Transfer Molding (RTM) process. Thus, three samples were considered, not strengthened matrix samples, samples with two layers of glass and samples with two layers of glass and two layers of aluminum. Then amounts of rigidity, strength and density of the samples were calculated considering fibers volume fraction. The results indicate that the presence of aluminum layer leads to an increase in toughness and plasticity of the composite, and thus causes more resistance to damage. Besides ultimate strength and strain, Natural frequency of the samples also increases by addition of the aluminum layer.