Joining of SiC Ceramic to Graphite Using Ni-51Cr Powders as Filler

2008 ◽  
Vol 368-372 ◽  
pp. 1600-1602 ◽  
Author(s):  
Yang Wu Mao ◽  
Shu Jie Li ◽  
Lian Sheng Yan
Keyword(s):  
High Temperature ◽  
Chemical Reactions ◽  
Reaction Layer ◽  
Bending Strength ◽  
Weld Zone ◽  
High Strength ◽  
Interfacial Area ◽  
Three Point Bending ◽  
Sic Ceramic ◽  
Points Of View

Joining of SiC ceramic to graphite is important from both technical and economical points of view. High temperature brazing of recrystallized SiC ceramic to high strength graphite has been realized using Ni-51Cr (consisting of Ni + 51wt% Cr powders) powders as filler. The obtained maximum three-point bending strength of joints is 32.3MPa, which is equal to 80.8% of the strength of the graphite. Microstructure and phase analysis reveals that interdiffusions and chemical reactions take place in the weld zone. A reaction layer and an interlayer form in the interfacial area. The reaction layer, of which the thickness is about 60-100μm, is contacted with the SiC ceramic. The interlayer with the thickness of about 200μm exists between the graphite and the reaction layer. The reaction layer is mainly composed of Ni2Si, while the interlayer is mainly composed of Cr23C6 and Ni2Si.

Joining of SiC Ceramic to High Strength Graphite Using Polysiloxane with Active Additive

2007 ◽  
Vol 353-358 ◽  
pp. 2092-2095
Author(s):  
Shu Jie Li ◽  
Xiao Kun Yuan ◽  
Ting Zhang ◽  
Yang Wu Mao ◽  
Lian Sheng Yan
Keyword(s):  
Bending Strength ◽  
Weld Zone ◽  
Base Material ◽  
High Strength ◽  
Interfacial Area ◽  
Weld Strength ◽  
Technological Parameters ◽  
Orthogonal Experiments ◽  
Sic Ceramic ◽  
Active Additive

In order to contribute to the development of the joining technique of Cf/SiC, joining of SiC ceramic to high strength graphite was investigated. This joining has been successfully realized by reaction joining process using a preceramic polymer, polysiloxane, mixed with the active additive Al-Si powder as joining material. The weld strength is strongly affected by the technological parameters and the ingredient ratio (polysiloxane:Al-Si powder). The optimized factors have been obtained by orthogonal experiments, under which the achieved three-point bending strength of the joints is 96.8% of the strength of the welding base material graphite. The microstructure and composition of the weld zone were analyzed by SEM, EDX and XRD. The results show that the joining material has transformed into a densified interlayer with the thickness of about 15μm. Also, diffusion takes place in the interfacial area, which contributes to a sound interfacial bonding. The interlayer is composed of SiC, Al2O3 and Si.

Joining of SiC Ceramic by High Temperature Brazing Using Ni-Cr-SiC Powders as Filler

2007 ◽  
Vol 336-338 ◽  
pp. 2394-2397
Author(s):  
Shu Jie Li ◽  
Yang Wu Mao ◽  
Yue Hui He
Keyword(s):  
High Temperature ◽  
Bending Strength ◽  
Weld Zone ◽  
Base Material ◽  
Product Layer ◽  
Weld Strength ◽  
Technological Parameters ◽  
Major Phase ◽  
Sic Ceramic ◽  
Filler Mass

Joining of ceramics is of importance from both technical and economical points of view. Brazing is a widely used process to join ceramics. In order to increase the working temperature and weld strength of joints, a high temperature brazing process using Ni-Cr-SiC powders (consisting of Ni, Cr and SiC powders) as filler to join recrystallized SiC ceramic has been investigated. The obtained optimized technological parameters are joining temperature of 1360°C, holding time of 5min and filler mass of 280mg. Under these conditions the maximum relative bending strength of joints, 70.5%, is achieved. Microstructure and phase analysis reveals that interdiffusions and chemical reactions take place in the weld zone. A reaction layer, of which the major phase is Ni2Si, exists between the welding base material SiC ceramic and the filler reaction product layer, called as interlayer, of which the major phase is Cr23C6.

Low-Temperature Sintering of Porous Silicon Carbide Ceramics with H3PO4 as an Additive

2018 ◽  
Vol 281 ◽  
pp. 311-315 ◽  
Author(s):  
Tian Gu ◽  
Fei Chen ◽  
Hai Long Yuan ◽  
Qiang Shen ◽  
Lian Meng Zhang
Keyword(s):  
Phosphoric Acid ◽  
Bending Strength ◽  
Sintering Temperature ◽  
High Strength ◽  
High Porosity ◽  
Low Temperature Sintering ◽  
Sic Ceramic ◽  
Carbide Ceramics ◽  
Porous Sic ◽  
Silicon Carbide Ceramics

In this paper, the raw SiC powder is oxidized at high temperature (1000 °C for 4h), and a layer of SiO2oxide film is formed on the surface of SiC particles. By adding phosphoric acid, phosphoric acid reacts with SiO2at lower temperatures to form phosphate. Phosphate decomposition produces gas to create pores. At 1200 °C, the phosphate is completely decomposed into SiO2, and a large amount of gas is produced to prepare porous SiC ceramic with high porosity and high strength. The effects of H3PO4content on the phase composition, microstructure, porosity and mechanical properties of the prepared porous SiC ceramic were investigated. With the increase of H3PO4content, the porosity increased and the bending strength decreased. The results suggest that at the sintering temperature of 1200 °C, the porosity of the samples can reach 58.3%~71.2%, while the bending strength of them can reach 8.72~31.09 MPa.

Pressureless Sintering of Ultra-High Temperature ZrB2-SiC Ceramics

2008 ◽  
Vol 368-372 ◽  
pp. 1746-1749 ◽  
Author(s):  
Zhi Qiang Cheng ◽  
Chang Ling Zhou ◽  
Ting Yan Tian ◽  
Cheng Gong Sun ◽  
Zhi Hong Shi ◽  
...  
Keyword(s):  
High Temperature ◽  
Bending Strength ◽  
Sintering Temperature ◽  
Ablation Rate ◽  
Ultra High Temperature Ceramics ◽  
Sintering Additive ◽  
Sic Ceramics ◽  
Ablation Resistance ◽  
Sic Ceramic ◽  
Ultra High Temperature

ZrB2-SiC ultra-high temperature ceramics (UHTCs) were pressureless sintered with Y2O3-Al2O3 as the sintering additives. The effects of sintering additive and crystallization annealing on the microstructure and properties of ZrB2-SiC UHTCs were investigated. Sintering was activated by producing liquid phase of Y2O3 and Al2O3. The relative density of sintered ZrB2-20wt%SiC ceramic could reach 96% when the content of sintering additive was 6% and the sintering temperature was 1750°C and its bending strength, Vickers hardness, and fracture toughness were 412 MPa, 13 GPa, and 6.0 MPa•m1/2, respectively. The crystallization annealing can result in YAG phase from grain boundary and enhance the high temperature properties of the UHTCs. The UHTCs have excellent ablation resistance at ultra-high temperatures, and a very low ablation rate of 0.0006 mm/s after ablation for 900s at 2800°C.

Bending Behavior of Glass Fiber Grid Reinforced Gussasphalt

2015 ◽  
Vol 744-746 ◽  
pp. 754-757
Author(s):  
Bo Gao ◽  
Min Wang ◽  
Zeng Heng Hao
Keyword(s):  
Composite Material ◽  
High Temperature ◽  
Glass Fiber ◽  
Bending Strength ◽  
Bending Test ◽  
Material Technology ◽  
Bending Performance ◽  
Three Point Bending ◽  
Bending Strain ◽  
Bending Behavior

In combination with the composite material technology, add the glass fiber grid into gussasphalt deck pavement system to form glass fiber grid reinforced gussasphalt. Analysis shows that adding the grid can increase the bending performance. Three point bending test was did to do verification and results were indicate that glass fiber grid can improve the anti-bending strength and anti-bending strain in high temperature.

Effect of Li2O, K2O and ZnO on Vitrified Bond Composites for CBN Grinding Wheels

2016 ◽  
Vol 874 ◽  
pp. 193-198 ◽  
Author(s):  
Zi Xuan Wang ◽  
Tian Biao Yu ◽  
Ji Zhao ◽  
Xue Zhi Wang ◽  
Xue Sun ◽  
...  
Keyword(s):  
Mechanical Property ◽  
High Temperature ◽  
Bending Strength ◽  
Gas Bubbles ◽  
Microstructure Analysis ◽  
Depth Of Field ◽  
Grinding Wheels ◽  
Three Point Bending ◽  
Vitrified Bond

To investigate the effect of Li2O, K2O and ZnO on SiO2-Al2O3-B2O3-Na2O vitrified bond for CBN grinding wheels, the refractoriness and fluidity of specimens with different additions were studied. The bending strength was measured by three-point bending tester and the microstructures were observed by super Depth-of-Field microscope. The results show that Li2O, K2O and ZnO can reduce the refractoriness and increase the high-temperature fluidity. Li2O and K2O make a contribution to improving the bending strength; however ZnO is harmful to specimens’ mechanical property. Additionally, the fluidity is important to control the number of gas bubbles in specimen according to the microstructure analysis.

scholarly journals Characterization of SiC Ceramic Joints Brazed Using Au–Ni–Pd–Ti High-Temperature Filler Alloy

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 931
Author(s):  
Huamin He ◽  
Chuanyang Lu ◽  
Yanming He ◽  
Wenjian Zheng ◽  
Jianguo Yang ◽  
...  
Keyword(s):  
High Temperature ◽  
Reaction Layer ◽  
Thermal Stresses ◽  
Fracture Morphology ◽  
Filler Alloy ◽  
Soaking Time ◽  
Sic Ceramics ◽  
Joint Fracture ◽  
Sic Ceramic

In this work, (Au79Ni17Pd4)96Ti4 (wt.%) filler alloy was designed and employed to join SiC ceramics. The effects of brazing temperature and soaking time on the microstructure and fracture morphology of joints were investigated. The results show that the joint obtained can be described as SiC/reaction layer/braze/reaction layer/SiC. The reaction layer was composed of TiC and Au (Si, Ti). The wettability of the filler alloy toward the SiC ceramics was analyzed. The braze zone was mainly constituted by Pd2Si, Ni2Si, and Au (Ni, Si). A large number of nano-sized TiC particles were distributed within the Au (Ni, Si) layer. The formation mechanism of the braze containing different phases was discussed. The brazing temperature and soaking time had a significant effect on the reaction layer at the SiC/braze interface and TiC particles within the Au (Ni, Si) layer, while they showed a negligible effect on the Pd2Si and Ni2Si within the braze. The inherent reason was also clarified in detail. The joint fractography indicated that a good bonding was achieved between the filler alloy and SiC, while joint fracture was primarily induced by the thermal stresses residing after the brazing cycle.

Study of High Temperature Performance and Low Temperature Property on Layered Silicate Modified Asphalt Concrete

2012 ◽  
Vol 509 ◽  
pp. 189-193 ◽  
Author(s):  
Shao Peng Wu ◽  
Tian Gui Liu ◽  
Ling Pang ◽  
Ting Wei Cao ◽  
Pan Pan
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Asphalt Concrete ◽  
Bending Strength ◽  
Layered Silicate ◽  
Temperature Property ◽  
Three Point Bending ◽  
Modified Asphalt ◽  
Temperature Performance ◽  
Low Temperature Property

Montmorillonite (MMT), a typical layered silicate, has been widely used to prepare modified asphalt. This paper investigates the high temperature performance and low temperature property on layered silicate modified asphalt concrete. The control concrete is prepared by base asphalt. Meanwhile, three-point bending, conventional and SHRP rutting tests are used to compare the properties of the two types of asphalt concrete. The results of conventional and SHRP rutting tests show that the modified asphalt concrete exhibits a better high temperature performance than the control concrete. And the maximum bending strength of modified asphalt concrete is higher than that of control concrete at the same temperature. It can be concluded that both the high temperature performance and low temperature property of asphalt concrete has been improved efficiently by utilization of layered silicate modified asphalt.

Oxidation Resistance and Bending Strength at High Temperatures of Ni/(ZrO2+Al2O3) Hybrid Materials

2018 ◽  
Vol 922 ◽  
pp. 104-109
Author(s):  
Hai Vu Pham ◽  
Makoto Nanko ◽  
Wataru Nakao
Keyword(s):  
High Temperature ◽  
Oxidation Resistance ◽  
Cross Section ◽  
High Temperatures ◽  
Room Temperature ◽  
Bending Strength ◽  
Bending Tests ◽  
Three Point Bending ◽  
Order Of Magnitude ◽  
Zone Development

Oxidation resistance and bending strength at high temperatures of 5 vol% Ni/(10 vol% ZrO2+Al2O3) were investigated in this paper. Oxidation tests were conducted at temperature ranging from 1100 to 1300oC for 1 to 24 h in air. The oxidation resistance of the composites was studied via observation of oxidized-zone development from a cross-section view after oxidation. Three-point bending tests were conducted at temperatures ranging from room temperature to 1200oC in order to estimate its performance at high temperatures. Bending strength of the composites achieved 1200 MPa at room temperature and 460 MPa at 1200oC. Dispersion of ZrO2in Ni/Al2O3composites enhanced both their room and high temperature bending strength. Nevertheless, ZrO2slightly degraded the oxidation resistance of the composites. The oxidation rate of Ni/(ZrO2+Al2O3) was one order of magnitude higher than that of Ni/Al2O3.

Joining of SiC Ceramic by Hot Pressing Reaction Joining Process Using Ni-51Cr Powders as Filler

2007 ◽  
Vol 336-338 ◽  
pp. 2398-2401 ◽  
Author(s):  
Yang Wu Mao ◽  
Shu Jie Li ◽  
Yan Zhang
Keyword(s):  
Hot Pressing ◽  
Bending Strength ◽  
Orthogonal Experiment ◽  
Weld Zone ◽  
Base Material ◽  
Product Layer ◽  
Weld Strength ◽  
Technological Parameters ◽  
Sic Ceramic ◽  
Joining Process

Joining of ceramics is of importance from both technical and economical points of view. Joining of recrystallized SiC ceramic to itself has been realized by hot pressing reaction joining process using Ni-51Cr powders (consisting of Ni+51wt%Cr powders) as filler. The optimized technological parameters have been obtained by orthogonal experiment, which are joining temperature of 1150°C, holding time of 20min, joining pressure of 10MPa and cooling rate of 0.25°C/s. The most effective factor to influence the weld strength is joining pressure within the range of testing. Under the optimized conditions, the maximum relative bending strength of joint, 70.7%, is achieved. The microstructure and phase composition of the weld zone were examined by SEM, EDX and XRD. The results show that interdiffusions and chemical reactions take place in the joining process. A reaction layer, which is mainly composed of Ni2Si and Ni3C with a little Cr, exists between the welding base material SiC ceramic and the filler reaction product layer called as interlayer, which is mainly composed of Ni2Si and Cr.

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