Molecular Dynamics Study on SiO2 Interfaces of Nonfiring Solids

As a sustainable ecosystem, the general firing process for ceramics emits large amounts of CO2 gas; thus in ceramics production, the focus is the nonfiring process; however, the solidification and strengthen mechanism of this nonfiring system, which essentially reacts between surface-activated ceramic particles and a solvent, has not been elucidated to date. The nonfiring process had three steps, i.e., particle surface activate process by grinding process, maintaining the active state until starting nonfiring solidification begins, and nonfiring solidification process. Thus, in this study, the reaction of silica and water was simulated by adapting molecular dynamics based on LAMMPS with ReaxFF potentials. Reproducing the activated silica surface state, three ended models called O model, Si model, and OH model were prepared which indicated ended molecules of each surface. These models and a water molecule as a solvent were bonded in the atomic scale, and the energetic state and mechanical properties were evaluated. A reacted or structured O-H-O bond was reproduced in the nonfiring process in the O-ended model. The bond was a hydrogen bond. A Si-O-Si bond was produced when a Si atom was ended on the interface. The bonded interface was able to tensile. However, the tensile strength was weaker than that of the solid silica model. The nonbonded OH model did not have tensile strength.

Phase Stability and Mechanical Properties of FCC Structural CoCrCu0.5FeNi High-Entropy Alloy with Silicon or Boron Addition

Microstructures, phase stability and properties of the as-solidified CoCrCu0.5FeNi(Si/B)x alloys were studied in this work. Intermetallic compounds are found when Si or B was added in a FCC structural CoCrCu0.5FeNi high-entropy alloy, and B possess a better intermetallic formation ability than Si. On the other, solute ability of Si is better than that of B in CoCrCu0.5FeNi alloy. The strength of CoCrCu0.5FeNi high-entropy alloy was improved after the addition of Si and B, and the strengthen mechanism was discussed. Moreover, parameter g can provide a reference to predict the ability of forming intermetallic compounds in CoCrCu0.5FeNi(Si/B)x alloys. The increase of δ is prone to the forming of intermetallic compounds. But the volume fraction of intermetallic compounds increase with the decrease of Ω in the same alloy system.

Research on the Strengthen of Silicone Rubber

A new kind of microsphere filler was synthesized with octyltrimethoxysilane (WD13) and tetraethoxysilane (TEOS) by sol-gel method. The morphology of the filler was measured by TEM. The so synthesized spheres were added into the silicone rubber. Both the strain-stress and the water contact angle of the silicone rubber were researched. The results showed that both the mechanical property and the hydrophobic performance of the composite were improved compared with the blank specimen. The possible strengthen mechanism of the filler was discussed. The neotype silica sphere researched in this paper could react with the silicone rubber chains which perfects the vulcanization of the silicone rubber. This kind of sphere filler exhibits many merits for usage as filler.

Research on a Neotype of Silica Sphere Filler

A neotype of silica microspheres were synthesized with chloropropyltrimethoxysilane (WD30) and tetraethoxysilane (TEOS) by sol-gel method. And the thermal properties of the filler both in nitrogen and in air condition were studied by means of thermogravimetric analysis. The morphology of the filler was measured by TEM. The so synthesized spheres were added into the silicone rubber whose mechanical strength was increased greatly. The molecular structure of the filler and the silicone rubber were characterized by FTIR. The possible strengthen mechanism of the filler was discussed. The neotype silica sphere researched in this paper could react with the PDMS chains which perfects the vulcanization of the silicone rubber. This kind of silica sphere exhibits many merits for usage as filler.