The composites were prepared by modifying silicon carbide fiber with particles of zirconium carbide(ZrC)and boron carbide(B_(4)C)and incorporating them into a phenolic resin matrix.The influence of ZrC and B_(4)C on t...The composites were prepared by modifying silicon carbide fiber with particles of zirconium carbide(ZrC)and boron carbide(B_(4)C)and incorporating them into a phenolic resin matrix.The influence of ZrC and B_(4)C on the mechanical performance of SiCf/phenolic composites after high-temperature pyrolysis was studied through flexural performance test.The results show that the composite material has good thermal stability and high-temperature mechanical properties.After static ablation at 1400℃ for 15 minutes,the flexural strength of the composite material reaches 286 MPa,which is still 7.3%higher than at room temperature,indicating that the composite material still has good mechanical properties even after heat treatment at 1400℃.展开更多
The PZT thin films were prepared on （111）- Pt/Ti/SiO2/Si substrates by sol-gel method, and lead acetate [Pb（CH3COO）2], zirconium nitrate [Zr（NO3）4] were used as raw materials. The X-ray diffractometer （XRD） an...The PZT thin films were prepared on （111）- Pt/Ti/SiO2/Si substrates by sol-gel method, and lead acetate [Pb（CH3COO）2], zirconium nitrate [Zr（NO3）4] were used as raw materials. The X-ray diffractometer （XRD） and scanning electron microscopy （SEM） were used to characterize the phase structure and surface morphology of the films annealed at 650 ~C but with different holding time. Ferroelectric and dielectric properties of the films were measured by the ferroelectric tester and the precision impedance analyzer, respectively. The PZT thin films were constructed with epoxy resin as a composite structure, and the damping properties of the composite were tested by dynamic mechanical analyzer （DMA）. The results show that the films annealed for 90 minutes present a dense and compact crystal arrangement on the surface; moreover, the films also achieve their best electric quality. At the same time, the largest damping loss factor of the composite constructed with the 90 mins-annealed film shows peak value of 0.9, hi^her than the pure epoxy resin.展开更多
TiSi_(2) reinforced boron phenolic composites(TP)and Vitreous silica fabric reinforced TiSi_(2)/boron phenolic composites(VTP)were prepared by compression molding,and their thermal,mechanical,ablation properties were ...TiSi_(2) reinforced boron phenolic composites(TP)and Vitreous silica fabric reinforced TiSi_(2)/boron phenolic composites(VTP)were prepared by compression molding,and their thermal,mechanical,ablation properties were studied.TG results show that thermal stabilities and residual carbon rate of boron phenolic are improved after introducing TiSi_(2) particles.Compared with VTP-0(containing 0 phr TiSi_(2)),flexural strength of VTP-60(containing 60 phr TiSi_(2))pyrolysis product increases by 29.5%at 1200℃.Raman spectrum shows that TiSi_(2) particles promote the ordering of the glass carbon structure of VTP pyrolysis product.Compared to VTP-0,the linear and mass ablation rates of VTP-60 reduce by 32.1%and 77.5%,respectively.XRD and SEM indicate the formation of an oxide coating layer,TiO_(2)-SiO_(2),integrates the bulk and protects the underlying materials from damage under high temperature oxygen-containing airstream.All these results prove that mechanical properties of pyrolysis product,thermal,and ablation resistance are improved by addition of TiSi_(2) particles.展开更多
基金Funded by the Joint Fund of Ministry of Education for Equipment Pre-research(No.6141A02022250)the Fundamental Research Funds for the Central Universities,China(No.WUT:2021III003XZ)。
文摘The composites were prepared by modifying silicon carbide fiber with particles of zirconium carbide(ZrC)and boron carbide(B_(4)C)and incorporating them into a phenolic resin matrix.The influence of ZrC and B_(4)C on the mechanical performance of SiCf/phenolic composites after high-temperature pyrolysis was studied through flexural performance test.The results show that the composite material has good thermal stability and high-temperature mechanical properties.After static ablation at 1400℃ for 15 minutes,the flexural strength of the composite material reaches 286 MPa,which is still 7.3%higher than at room temperature,indicating that the composite material still has good mechanical properties even after heat treatment at 1400℃.
基金Supported by the National Natural Science Foundation of China (No. 50772083)China-Japan Cooperation Program(No. 2010DFA51270)the Fundamental Research Funds for the Central Universities
文摘The PZT thin films were prepared on （111）- Pt/Ti/SiO2/Si substrates by sol-gel method, and lead acetate [Pb（CH3COO）2], zirconium nitrate [Zr（NO3）4] were used as raw materials. The X-ray diffractometer （XRD） and scanning electron microscopy （SEM） were used to characterize the phase structure and surface morphology of the films annealed at 650 ~C but with different holding time. Ferroelectric and dielectric properties of the films were measured by the ferroelectric tester and the precision impedance analyzer, respectively. The PZT thin films were constructed with epoxy resin as a composite structure, and the damping properties of the composite were tested by dynamic mechanical analyzer （DMA）. The results show that the films annealed for 90 minutes present a dense and compact crystal arrangement on the surface; moreover, the films also achieve their best electric quality. At the same time, the largest damping loss factor of the composite constructed with the 90 mins-annealed film shows peak value of 0.9, hi^her than the pure epoxy resin.
基金Funded by the Joint Foundation for Pre-research Equipment of the Ministry of Education,China(Nos.6141A02022208 and 6141A02022250)the Fundamental Research Funds for the Central Universities(WUT,2021III005GX)。
文摘TiSi_(2) reinforced boron phenolic composites(TP)and Vitreous silica fabric reinforced TiSi_(2)/boron phenolic composites(VTP)were prepared by compression molding,and their thermal,mechanical,ablation properties were studied.TG results show that thermal stabilities and residual carbon rate of boron phenolic are improved after introducing TiSi_(2) particles.Compared with VTP-0(containing 0 phr TiSi_(2)),flexural strength of VTP-60(containing 60 phr TiSi_(2))pyrolysis product increases by 29.5%at 1200℃.Raman spectrum shows that TiSi_(2) particles promote the ordering of the glass carbon structure of VTP pyrolysis product.Compared to VTP-0,the linear and mass ablation rates of VTP-60 reduce by 32.1%and 77.5%,respectively.XRD and SEM indicate the formation of an oxide coating layer,TiO_(2)-SiO_(2),integrates the bulk and protects the underlying materials from damage under high temperature oxygen-containing airstream.All these results prove that mechanical properties of pyrolysis product,thermal,and ablation resistance are improved by addition of TiSi_(2) particles.
