Carbon Fiber and Nickel Coated Carbon Fiber-Silica Aerogel Nanocomposite as Low-Frequency Microwave Absorbing Materials

Research Development in Silica Aerogel Incorporated Cementitious Composites—A Review

This paper presents an analysis of research results for silica aerogel cement composites over the past twenty years. Recently, two trends in the development of these composites have been noted, towards structural applications and towards ultralight composites for coatings and renders. Ongoing research shows that important aspects of cementitious composites with good mechanical performance are the proper selection of aggregates and improved adhesion at the silica aerogel–cement binder interface, which will guarantee high compressive strength with the lowest possible thermal conductivity. The best physicomechanical performance of aerogel cement composites with low thermal conductivity below 0.03 W/(m·K) was obtained when cenospheres and aerogel were used in a weight percentage of 5%. In turn, the prerequisites for using aerogel cement composites as coatings for energy-efficient building façades are the use of large amounts of silica aerogel as a substitute for lightweight aggregates or the selection of an optimal composition of lightweight aggregates and aerogel, ensuring the lowest possible thermal conductivity coefficient. Other important standpoints are water transport and moisture protection of the silica aerogel-based coatings. Therefore, in recent years, more and more elements of the hygrothermal performance, porosity and durability of silica aerogel cement composites have been developed. The article also points out the weaknesses of the application of silica aerogel in the cement matrix, the most important of which are the lack of adhesion at the boundary of the aerogel–cement binder, the increased porosity of the composite, the high water absorption capacity and the significant decrease in compressive strength with large volumes of silica aerogel. Solving these issues will certainly contribute to the wider applicability of these materials in the construction industry.

Carbon Fiber-Silica Aerogel Composite with Enhanced Structural and Mechanical Properties Based on Water Glass and Ambient Pressure Drying

The article presents the synthesis of silica aerogel from a much cheaper precursor of water glass that was reinforced with short pitch carbon fiber by way of ambient pressure drying. Before being added to the silica gel, the carbon fibers were surface modified to increase adhesion at the interfacial border. We were able to obtain stable structures of the composite with the amount of fibers above 10% by volume. The presence of fibers in the silica matrix resulted in lower synthesis time of the composite, improved adhesion of fibers to the aerogel nanostructure, and increased mechanical and structural parameters. An additional effect of the presence of fibers in excess of 10% by volume was a new function of the nanocomposite—the ability to conduct electric current. The most optimal parameters of the composite, however, were obtained for silica aerogel reinforced with 10 vol.% of carbon fibers. This material indicated relatively low density and good physical parameters. The paper also analyzes the results on the synthesis of fiber-reinforced silica aerogels that have appeared in recent years and compares these to the results gained in presented work.

Fabrication and Characterization of Carbon-Fiber-Reinforced Polymer-FeSi Composites with Enhanced Magnetic Properties

In this work, we aimed to manufacture and characterize carbon-fiber-polymer-metal-particles magnetic composites with a sandwichlike structure. The composites were manufactured by stacking the plain woven carbon fiber prepregs (or carbon-fiber-reinforced polymers (CFRP)) and layers of the FeSi particles. The layer of FeSi particles were formed by evenly distributing the FeSi powder on the surface of carbon fiber prepreg sheet. The composites were found to have better magnetic properties when the magnetic field were applied in in-plane (0°) rather than in through-thickness (90°), and the highest saturation magnetization of 149.71 A.m2/kg was achieved. The best inductance and permeability of 12.2 μH and 13.08 were achieved. The composites obviously exhibited mechanical strength that was good but lower than that of CFRP composite. The lowest tensile strength and lowest flexural strength were 306.98 MPa and 855.53 MPa, which correspond to 39.58% and 59.83% of the tensile strength and flexural strength of CFRP (four layers), respectively.