Effect mechanism of mono-particles or hybrid-particles on the thermophysical characteristics and mechanical properties of Cu matrix composites

The nature of ceramic particles plays a decisive role in the performance of the ceramic/metal composites. This work is designed to deeply analyze the effect of mono-particles and hybrid-particles on the thermal and mechanical characteristics of the composites by means of experiment and finite element analysis. The in-situ TiB₂/Cu and (TiC + TiB₂)/Cu composites were fabricated by reactive hot pressing in Cu–Ti–B and Cu–Ti–B₄C reaction systems. The two kinds of composites have similar coefficient of thermal expansion, while the (TiC + TiB₂)/Cu composite demonstrates higher thermal conductivity and better compression properties than the TiB₂/Cu composite. Simulations suggest that the spherical TiC particles in the (TiC + TiB₂)/Cu composite optimize the heat transfer path and improve the stress distribution and plastic deformation, which are the main reasons for the difference in composite properties. Besides, the TiB₂/Cu composite demonstrates excellent wear resistance due to the pinning effect of the hexagonal columnar particles. This would help deepen the understanding of the strengthening mechanism of mono-particles or hybrid-particles ceramic reinforced metal matrix composites and have a significant guiding role in the microstructure design and synergy optimization of composite.     

Effects of carbon additives on the properties of ZrB2–based composites: A review

This review presents the recent achievements on carbon additives incorporated in ZrB₂ ceramics, improved properties, and their advancements. Monolithic ZrB₂ ceramics have broad potential applications, but their critical drawbacks such as poor damage tolerance, and weak oxidation and ablation resistance confines their applicability. It is an important issue to resolve these shortages in physiochemical properties by engineering the composite ingredients and process design of the ceramic counterparts for an extensive production and applications, which are especially essential in high–tech industries and products. Carbon additives have exceptional characteristics including low density, low cost, and excellent thermo–mechanical stability. These materials have been incorporated in ZrB₂ ceramics to enhance their efficiency and form practical composite ceramics. Although addition of the secondary carbonaceous phases is generally supposed to improve the mechanical properties of ZrB₂ composites, it may also result in a decrease in other aspects of performance, comparing with monolithic ZrB₂ ceramics. In this work, we reviewed the methods and strategies for the preparation of carbon modulated ZrB₂ ceramic composites. Moreover, the advantages, disadvantages, and the productivity of the introduced composite ceramics have been explored and featured.     

Dielectric,Mechanical, and Thermal Properties of Low-Permittivity Polymer–Ceramic Composites for Microelectronic Applications

A new low-permittivity polymer–ceramic composite for packaging applications has been developed. The ceramic-reinforced polyethylene and polystyrene composites were prepared by melt mixing and hot molding techniques. Low-loss, low-permittivity Li₂MgSiO₄ (LMS) ceramics prepared by the solid-state ceramic route were used as the filler to improve the dielectric properties of the composites. The relative permittivity and dielectric loss were increased with the increase in the ceramic loading at radio and microwave frequencies. The mechanical properties and thermal conductivity of the Li₂MgSiO₄-reinforced polymer–ceramic composite were also investigated. The stability of the relative permittivity of polymer–ceramic composites with temperature and frequency was investigated. The experimentally observed relative permittivity, thermal expansion, and thermal conductivity were compared with theoretical models.     

Effect of the filler morphology on the crystallization behavior and dielectric properties of the polyvinylidene fluoride-based composite

Ceramic/polymer composites can be chemically stable, mechanically strong, and flexible, which make them candidates for electric devices, such as pressure or temperature sensors, energy storage or harvesting devices, actuators, and so forth. Depending on the application, various electrical properties are of importance. Polymers usually have low dielectric permittivity, but increased dielectric permittivity can be achieved by the addition of the ceramic fillers with high dielectric constant. With the aim to enhance dielectric properties of the composite without loss of flexibility, 5 wt% of BaTiO₃-Fe₂O₃ powder was added into a polyvinylidene fluoride matrix. The powder was prepared by different synthesis conditions to produce core/shell structures. The effect of the phase composition and morphology of the BaTiO₃-Fe₂O₃ core/shell filler on the structure and lattice dynamics of the polymer composites was investigated. Based on the results of the thermal analysis, various parameters of ceramic/polymer composites were determined. Differences in the phase composition and morphology of the filler have an influence on the formation of various polyvinylidene fluoride allomorphs and the degree of crystallinity. Furthermore, the dielectric performances of pure polyvinylidene fluoride and the polymer/ceramic composites were measured.     

Experiments and modeling of thermal conductivity of flake graphite/polymer composites affected by adding carbon-based nano-fillers

Enhancement of thermal conductivity of natural flake graphite/polymer (NFG/polymer) composite sheets, prepared with tape casting method, was studied by adding carbon-based nano-fillers including carbon black, carbon nanotube (CNT) and graphene. The in-plane thermal conductivities of the composites, i.e., the thermal conductivities along the tape casting plane, were measured. The improvement of thermal conductivities of the composites was observed to be up to 24% by adding CNT and 31% by adding graphene at 10 wt.%. Micro-structures of the NFG/polymer composites were revealed by X-ray diffraction patterns and field emission scanning electron microscopy images to delineate the mechanism of thermal conductance in the composites. From the observed structure, a new thermal conductivity model for the composites with CNT and graphene additives was constructed based on a bridging mechanism. The new model applies well to the measured thermal conductivities of the as-prepared samples. It is expected that the model could also be applied well to composites added with other homologous materials for bridging thermal contacts.     

Effect of acid-treatment and colloidal-processing conditions on the room temperature mechanical and electrical properties of 3YTZP/MWNT ceramic nanocomposites

Different colloidal powder processing routines have been used to prepare composites of 3 mol% Y₂O₃ -ZrO₂ (tetragonal zirconia polycrystals, 3YTZP) with 2.5 vol% multiwall carbon nanotubes (MWNT) with the aim of achieving a homogeneous distribution of the MWNTs in the ceramic, eliminating agglomerates but also minimizing carbon nanotube (CNT) damage during processing. Modifications of the acid treatment applied to the nanotubes, including subjecting them to stirring or ultrasonic agitation, and use of acid or basic pH during composite powder mixing have been approached.No MWNT damage during processing was detected by Raman spectroscopy. CNT bundles were found in all the composites forming different patterns depending on the processing route. Similar values of hardness were obtained for all the composites, while different anisotropy in fracture propagation was found when studying parallel and perpendicular directions to the sintering pressing axis on the cross sections of the composites due to the MWNT preferential alignment. The CNT bundles were found to act as fracture short paths. A similar anisotropic behavior was observed for the electrical conductivity. These results have been correlated to the different microstructures obtained in the composites prepared with different processing routines.     

Thermal properties of low loss PTFE‐CeO2 dielectric ceramic composites for microwave substrate applications

Polytetrafluroethylene (PTFE) composites filled with CeO₂ were prepared by powder processing technique. The PTFE is used as the matrix and the loading fraction of CeO₂ in the composite varied up to 0.6 volume fraction. The thermal conductivity and coefficient of thermal expansion were studied in relation to filler concentration. The thermal conductivity increased and coefficient of thermal expansion decreased with increase in CeO₂ content. For 0.6 volume fraction loading of the ceramic, the composite has a thermal conductivity of 3.1 W/m°C and coefficient of thermal expansion 19.6 ppm/°C. Different theoretical approaches have been employed to predict the effective thermal conductivity and coefficient of thermal expansion of composite systems and the results were compared with the experimental data. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Study on the ablative properties of ethylene propylene diene terpolymer/silsesquioxane insulation materials

Octaphenylsilsesquioxane (OPS), polyphenylsilsesquioxane (PPSQ), and octavinylsilsesquioxane (OVP) have been incorporated into ethylene propylene diene terpolymer (EPDM) in order to study their effects on the ablative properties of the respective EPDM composites. The results show that PPSQ and OVP serve as effective ablative additives for EPDM composites. The linear ablation rates of EPDM composites with 4.4 wt % OVP or PPSQ were reduced by 21 or 16.5%, respectively, compared with the control sample. Moreover, OVP and PPSQ also improved the flame retardancy and suppressed smoke emission. The heat release rate of EPDM composite with 4.4 wt % OVP was measured as 90.6 kW m⁻², 17% lower than that of the control sample, and the same amount of PPSQ reduced the total smoke release from 1946 to 1497 m² s⁻¹. Thermogravimetric analysis results showed EPDM/OVP composite to leave a higher residual mass than the calculated value. Besides, scanning electron microscopy, cone calorimetry (CONE), and BET tests showed that the chars formed during the ablation of EPDM composites containing OVP and PPSQ had better structural stability and thermal stability owing to the fact that they were denser and more homogeneous. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48365.     

Preparation of an environment-friendly LTCC material by using waste soda-lime glass and natural volcanic ash

Glass/ceramic composites applied in the field of low-temperature co-fired ceramics (LTCC) were successfully prepared at 670–710 °C by using waste soda-lime glass (WG) as a binder and natural volcanic ash as a ceramic raw material. Based on the theories of suppression and supplementary network effects, alkaline-earth metal ions (R²⁺, R = Mg, Ca, Sr, and Ba) and B₂O₃ were applied to improve the dielectric properties of WG and composites, respectively. The influence of R²⁺ on the crystal phase evolution, microstructure, mechanical, dielectric, and thermal properties of WG-volcanic ash-based composites were systematically investigated. By doping 2.5 wt% Ba²⁺ to the environment-friendly LTCC composites, physical properties i.e., ε_r of 4.86 at 1 MHz, tan δ of 6.32 × 10^?3, coefficient of thermal expansion of 8.72 × 10^?6/°C, and thermal conductivity of 1.04 W/(m·K) are obtained. It is worth mentioning that the environment-friendly LTCC composite uses WG with a low glass transition temperature to reduce the sintering temperature and a tiny amount of a modifier to adjust the dielectric performance instead of synthesizing specific crystals by adding lots of chemical reagents. These, in turn, do not only have the potential to be used in the LTCC packaging technology but also have significance for sustainable development. Additionally, because of good chemical compatibility between aluminum and the composites, the environment-friendly LTCC composites with ultra-low sintering temperature have the potential ability to lower the cost of LTCC packaging materials.     

Morphology and anti-ablation properties of composites nozzles under the Ф100mm H2O2- polyethylene hybrid rocket motor test

Environmentally friendly commercial applications spurred us to screen a suitable ablative throat material for the hybrid rocket, while preserving its cost-effective advantages as a special chemical motor. In this research, two types of carbon fiber reinforced composites, i.e. carbon/carbon (C/C) composite and C_f/C–SiC–ZrC composite utilized in high temperature environment, were employed to make the hybrid rocket nozzle. By comparison with the high-density graphite, the anti-ablation properties under the firing environment of Ф100mm H₂O₂-polyethylene hybrid rocket motor were characterized. We used whole felt preform to make C/C composite, whose matrix carbon was coming from chemical vapor infiltration of propylene; and the C_f/C–SiC–ZrC composite, which employs the same whole felt preform to make the low-density C/C billet, by infiltrated with Si and Zr organic precursors and pyrolysis at elevated temperatures repeatedly to make the advanced ceramic matrix composite. The firing test lasted 40s for all the candidate materials and the result indicated that the C_f/C–SiC–ZrC composite, whose average linear ablation rate was only 0.003 mm/s, was the most stable one in the firing environment. The SEM images gave detailed morphologies of those nozzle throat materials and proved that the fiber architecture, together with the glassy ceramic oxide, helped the nozzle to withstand the hybrid motor firing environment.     

Experimental investigation of mechanical,thermal, and ablation performance of ZrO2/SiC modified C-Ph composites

In this study, an effort has been made to improve the mechanical, thermal, and ablation performance of carbon-phenolic (C-Ph) composites. The ZrO₂, SiC, and ZrO₂/SiC hybrid fillers were synthesized using sol-gel method followed by individual incorporation into C-Ph composites. The thermal stability and flexural strength of these C-Ph composites were analyzed using thermogravimetry analysis and three-point bending test, respectively. A significant improvement in the flexural strength and modulus of the reinforced C-Ph composites was observed and also exhibited the higher thermal stability. The oxyacetylene flame test was conducted to measure the ablation behavior of these filler reinforced C-Ph composites under a heat flux of 4.0 MW/m² for 60 seconds. ZrO₂/SiC0.5 reinforcement in the C-Ph composite decreased the linear and mass ablation rates by 46% and 22%, respectively when compared with pure C-Ph composite. The surface morphology analysis revealed that the burnt composite covered with the ZrC ceramic phase and SiO₂ bubble-like structure, which could have improved the ablation resistance of composites. These results were found well within the acceptable range when using the surface energy dispersive spectroscopy and X-ray diffraction analysis.     

Effect of silane coupling agent on the dielectric and thermal properties of DGEBA-forsterite composites

Diglycidyl ether of bisphenol A (DGEBA) -forsterite composites have been prepared through mechanical mixing process and the influence of silane coupling agent on the microstructure, dielectric and thermal properties were studied. Phase pure forsterite (Mg₂SiO₄) powder was prepared through solid state ceramic route. Filling fraction of forsterite in DGEBA matrix was varied from 10 to 40 vol%. The morphology and filler distribution of filled composite were studied by Scanning Electron Microscopy. Waveguide cavity perturbation technique was employed to measure the dielectric properties of composites. It is found that aminosilane treatment increased the dielectric constant and dielectric loss of the composites in both microwave and radio frequency ranges compared to composites prepared using untreated powders. Coefficient of thermal expansion of composites decreased with the forsterite addition and attains a relatively low value of 45 ppm/°C for composite containing 40 vol% surface treated filler.     

Microwave dielectric properties of flexible butyl rubber–strontium cerium titanate composites

Butyl rubber–strontium cerium titanate (BS) composites have been prepared by hot pressing. The tensile tests show that the BS composites are flexible. The dielectric properties of the composites have been investigated at 1 MHz and 5 GHz as a function of ceramic contents. The composite with volume fraction 0.43 of ceramic filler has a dielectric constant (ε_r) of 11.9 and dielectric loss (tan δ) 1.8 × 10^?3 at 5 GHz. The measured values of ε_r are compared with the effective values calculated using different theoretical models. The thermal conductivity of the composites is found to increase with ceramic contents and reaches a value of 4.5 Wm^?1 K^?1 for maximum filler loading 0.43 volume fraction. The coefficient of thermal expansion of the composites decreases gradually with filler loading and reaches a minimum value of 30.2 ppm °C^?1 at a volume fraction 0.43. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Thermal stability and ablation properties study of aluminum silicate ceramic fiber and acicular wollastonite filled silicone rubber composite

The thermal stability and ablation properties of silicone rubber filled with silica (SiO₂), aluminum silicate ceramic fiber (ASF), and acicular wollastonite (AW) were studied in this article. The morphology, composition, and ablation properties of the composite were analyzed after oxyacetylene torch tests. There were three different ceramic layers found in the ablated composite. In the porous ceramic layer, the rubber was decomposed, producing trimers, tetramers, and SiO₂. ASF and part of AW still remained and formed a dense layer. The SiO₂/SiC filaments in the ceramic layer reduced the permeability of oxygen, improving the ablation properties of the composites. The resultant ceramic layer was the densest, which acted as effective oxygen and heat barriers, and the achieved line ablation rate of the silicone composite were optimum at the proportion of 20 phr/40 phr (ASF/AW). Thermogravimetric analysis (TGA) confirmed that thermal stability of the composites was enhanced by the incorporation of ASF and AW. The formation of the ceramic layer was considered to be responsible for the enhancement of thermal stability and ablation properties. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39700.     

Review: Effect on physical,mechanical, and wear performance of ZrB2-based composites processed with or without additives

Because of unique combination of properties, ultra high temperature ceramics (UHTCs) are considered the most suitable material for applications in extreme environments as in hypersonic flights, atmospheric reentry, and rocket propulsion system. Processing of UHTCs especially ZrB₂-based ceramic composites with additives offer advantages in terms of simple processing methodology and excellent properties. Processing route highly controls the ceramic properties. Present review share out systematically and explain the processing strategies of ZrB₂-based ceramic composites––conventional, hot press or spark plasma sintering and their effect on microstructure features, physical, and mechanical properties and tribological performance. Present review suggests that it is possible to process full dense ZrB₂–SiC ceramic composite with ultrafine or nano size particles via fast sintering technique like spark plasma sintering and gives better mechanical and wear resistant properties.     

Electrophoretic deposition of ceramic coatings on ceramic composite substrates

Abstract

The applicability of electrophoretic deposition (EPD) for the fabrication of single layer and multilayer ceramic coatings on dense ceramic composite materials has been examined. Al₂O₃/Y-tetragonal zirconia polycrystal (TZP) functionally graded composites of tubular shape were successfully coated with a two layer coating comprising porous alumina and dense reaction bonded mullite layers. The dual layer coating structure was designed to eliminate the numerous cracks caused by volume shrinkage during sintering of the individual EPD formed layers. In another example, mullite fibre reinforced mullite matrix composites were coated with a thin layer of nanosized silica particles using EPD. The aim was to achieve a compressive residual stress field in the silica layer on cooling from sintering temperature, in order to increase composite fracture strength and toughness. The EPD technique proved to be a reliable method for rapid preparation of single layer and multilayer ceramic coatings with reproducible thickness and microstructure on ceramic composite substrates.     

A novel B–Si–Zr hybridized ceramizable phenolic resin and the thermal insulation properties of its fiber-reinforced composites

A novel B–Si–Zr hybridized ceramicizable resin(BSZ-PR) was fabricated by chemical reaction of boric acid, zirconium hydroxyl-containing polyhedral oligomeric silsesquioxane(Zr-POSS) and phenolic. The incorporation of boric acid and Zr-POSS improved the thermal stability of the resin effectively, and the residual carbon rate increased to 72.63% at 800 °C under nitrogen atmosphere. The flexural strength of carbon fiber/BSZ-PR and high silica fiber/BSZ-PR composites were increased by 25.7% and 175.5%, and linear ablation rates were reduced by 37% and 44.75%, respectively. It was discovered that the ceramic structures such as SiO₂, ZrO₂ and SiC can be formed at high temperatures as well as under extreme ablative conditions from both BSZ-PR and its fiber-reinforced composites, which may be the key to the improved thermal, ablative properties.     

Intelligent cooling structure design of "Z-pins like" silicon rods to enhance the ablation resistance of C/C-ZrC-SiC composites above 2500 °C

In order to improve the ablation resistance of C/C-ZrC-SiC composites by reducing the damage of the protective oxide layer, novel "Z-pins like" silicon rods, which were designed and fabricated by liquid phase sintering, were utilised as a dissipative agent. The microstructure evolution and thermal dissipation behaviour were investigated after ablating above 2500 °C for 300 s. After the "Z-pins like" silicon rods were implanted, the anti-ablative property of the C/C-ZrC-SiC composites was drastically improved by the dissipative thermal protection mechanism. The linear ablation rate of the "Z-pins like" silicon rod-reinforced C/C-ZrC-SiC composite was -0.28 μm/s, which is 112.72% lower than the unmodified composite. Additionally, the actual ablative temperature dropped approximately 357 °C, which enabled abundant SiO₂ to remain in the ablation centre. Furthermore, a dense SiO₂-rich oxide layer with a low oxygen diffusion coefficient is formed that covers the entire ablative surface.     

Enhanced Thermoelectric Performance of SmBaCuFeO5+δ/Ag Composite Ceramics

Polycrystalline SmBaCuFeO_5+δ/Ag composite ceramics have been synthesized by a traditional ceramic processing method. Phase composition and microstructural analyses indicate that with the introduction of Ag additives, the second phases of copper oxides and Ag appear in these composite ceramic samples. The hole concentration and molibility can be enhanced greatly by the addition of Ag particles, which results in a large increase in the electrical conductivity. The thermal conductivity behaviors show that phonons can be scattered effectively by point defects and mesoscale grain boundaries, which remain a slight change in thermal conductivity. A maximum ZT value 0.047 has been achieved at 1023 K in the SmBaCuFeO_5+δ/20 vol% Ag composite ceramic, and is about 16 times than the pure SmBaCuFeO_5+δ sample. Our results reveal that Ag addition is an effective way to enhance the thermoelectric properties.