Effect of preset interfacial ZrB2 particles on the microstructure and properties of C/C-AlSi composites

2021 ◽  
pp. 002199832110046
Author(s):  
Wei Feng ◽  
Chengwei Tang ◽  
Lei Liu ◽  
Jian Chen ◽  
Yang Zhang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Thermal Expansion ◽  
Thermal Shock ◽  
Retention Rate ◽  
Pressure Infiltration ◽  
Micro Scale ◽  
Before And After ◽  
Micro Morphology ◽  
Strength Retention ◽  
Fiber Fabric

ZrB2 particles were preset to the C-AlSi interface to improve oxidation resistance of C/C preform and adjust the microstructure of the interpenetrated C/C-AlSi composite prepared through pressure infiltration of eutectic AlSi into a fiber fabric based porous C/C skeleton. Micro-morphology investigations suggested that the AlSi textures were changed from dendritic to petals-like state, and the nano to micro-scale ZrB2 particles were dispersed into AlSi and affected the distribution of Al and Si nearby carbon. Tests demonstrated that C/C-AlSi have slight lower density and thermal expansion coefficient, and higher original compressive strength, while C/C-ZrB2-AlSi composites presented an outstanding strength retention rate after thermal shock. Fracture and micro-morphology indicated that the influence of the preset ZrB2 to the interface of carbon and alloy greatly affected the generation and propagation of cracks, which determined the diverse compression behaviors of the composites before and after thermal shock.

Effect of Nano-Al2O3 Particles Addition on Thermal Shock Resistance of ZTA/Cordierite Composites

2018 ◽  
Vol 281 ◽  
pp. 212-216
Author(s):  
Hai Tao Chen ◽  
Zi Jie Zhang ◽  
Ling Zhang ◽  
Hong Xia Lu ◽  
Kai Gao ◽  
...  
Keyword(s):  
Thermal Shock ◽  
Intergranular Fracture ◽  
Residual Strength ◽  
Thermal Shock Resistance ◽  
Retention Rate ◽  
Transgranular Fracture ◽  
Thermal Shock Test ◽  
Ultrasonic Dispersion ◽  
Shock Resistance ◽  
Strength Retention

ZTA/cordierite composites were prepared using ZrO2, Micro-Al2O3/Nano-Al2O3 and cordierite as raw materials by pressureless sintering. The influence of Nano-Al2O3 particles content on phase composition, microstructure and thermal shock resistance of ZTA/cordierite were investigated. The results show that m-ZrO2, t-ZrO2 and Al2O3 existed in the matrix and t-ZrO2 content increased with the increase of Nano-Al2O3 powders content. By adding Nano-Al2O3 powders and ultrasonic dispersion, which can refine grain and promote sintering, the grain size is uniform, the porosity is less and some grains were pulled out, the fracture mode changes from intergranular fracture to intergranular fracture and transgranular fracture. The thermal shock test was carried out at 300°C-1000°C, the critical thermal shock temperature of ZTA ceramic without adding cordierite and Nano-Al2O3 particles is 800°C and the residual strength retention rate of the material is only 32.4%. But by adding Nano-Al2O3 powers and ultrasonic dispersion 30 min,the residual strength retention rate, relative density, flexural strength and fracture toughness of ZTA/cordierite sintered at 1550°C for 4 h increased greatly and were up to 73.6%, 97.2%, 436 MPa and 4.6 MPa.m1/2, respectively.

Preparation and Oxidation Properties of Carbon/Carbon Composites with the Antioxidant SiC/NiCS Coating

2017 ◽  
Vol 727 ◽  
pp. 881-888
Author(s):  
Yi Li ◽  
Fan Hao Zeng ◽  
Ji An Liu ◽  
Zhi Huan Zou ◽  
Yi Gu
Keyword(s):  
Oxidation Resistance ◽  
Transition Layer ◽  
Bending Strength ◽  
Retention Rate ◽  
Isothermal Oxidation ◽  
Carbon Composites ◽  
Before And After ◽  
Oxidation Properties ◽  
Short Time ◽  
Strength Retention

In the paper, the SiC/NiCS coating on carbon/carbon composites was designed and prepared, and its oxidation properties was investigated. The SiC transition layer is prepared by embedding method while the NiCS coating by brushing slurry. Oxidation resistance of various coatings and the same coating sintered by different ways are analyzed through the isothermal oxidation experiment. The strength retention of the samples after oxidation is tested through the three-point bending experiment. The surface and cross section morphology of the coating before and after oxidation are observed by SEM, and crystalline phases of the coating are analyzed by XRD. According to the results, the coating have excellent short-time oxidation resistance, and the weightless rate with oxidation time presents linear increasing trend basically. With the increase of temperature, the weight-loss rate increases. The more serious oxidation is, the lower bending strength retention rate is. The integrity and density of the barrier layer and the across-running cracks of the silicon carbide transition layer are the main factors influencing the oxidation resistance of the sample.

Influence of the Zinc Sublayer Method Production and Heat Treatment on the Microhardness of the Composite Ni-Al2O3 Coating Deposited on the 5754 Aluminium Alloy

2014 ◽  
Vol 59 (1) ◽  
pp. 355-358
Author(s):  
M. Karaś ◽  
M. Nowak ◽  
M. Opyrchał ◽  
M. Bigaj ◽  
A. Najder
Keyword(s):  
Heat Treatment ◽  
Aluminium Alloy ◽  
Thermal Shock ◽  
Nickel Coating ◽  
Nickel Sulphate ◽  
Al2o3 Coating ◽  
Nickel Coatings ◽  
Watts Bath ◽  
Before And After ◽  
Zinc Interlayer

Abstract In this study, the effect of zinc interlayer on the adhesion of nickel coatings reinforced with micrometric Al2O3 particles was examined. Nickel coating was applied by electroplating on EN AW - 5754 aluminium alloy using Watts bath at a concentration of 150 g/l of nickel sulphate with the addition of 50 g/l of Al2O3. The influence of zinc intermediate coating deposited in single, double and triple layers on the adhesion of nickel coating to aluminium substrate was also studied. The adhesion was measured by the thermal shock technique in accordance with PN-EN ISO 2819. The microhardness of nickel coating before and after heat treatment was additionally tested. It was observed that the number of zinc interlayers applied does not significantly affect the adhesion of nickel which is determined by thermal shock. No defect that occurs after the test, such as delamination, blistering or peeling of the coating was registered. Microhardness of the nickel coatings depends on the heat treatment and the amount of zinc in the interlayer. For both single and double zinc interlayer, the microhardness of the nickel coating containing Al2O3 particles increased after heat treatment, but decreased when a triple zinc interlayer was applied.

EFFECT OF DDAVP ON PRIMARY HEMOSTASIS WITH CONGENITAL AFIBRINOGENEMIA

1987 ◽  
Author(s):  
M Taki ◽  
M Inagaki ◽  
T Miura ◽  
N Saito ◽  
T Meguro ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Retention Rate ◽  
Platelet Membrane ◽  
Bleeding Tendency ◽  
Primary Hemostasis ◽  
Prolonged Bleeding Time ◽  
Before And After ◽  
Congenital Afibrinogenemia ◽  
Von Willebrand ◽  
Platelet Functions

It has been reported recently that DDAVP might be an useful tool in the therapy and prevention of bleeding in patients with congenital afibrinogenemia (CA).To study the mechanism of its efficacy, changes in the platelet functions of a patient with CA were examined prior to, and one hour after, the infusion of DDAVP (0.4 μg/Kg). A patient with Glanzmann's thrombasthenia (GT) was also examined, to allow a study of the role of platelet membrane glycoprotein IIb/IIIa (GP IIb/IIIa), a deficient platelet in GT, in the resulting effects of the drug. When both patients were infused with DDAVP, the level of plasma von Willebrand factor (vWF) increased two- to fourfold, accompanied by an enhancement of ristocetin-induced platelet agglutination. The level of plasma fibrinogen was never changed.The prolonged bleeding time observed was markedly improved only in the CA patient, remaining unchanged in the GT patient, after the infusion of DDAVP. This indicates that DDAVP is effective in diminishing the bleeding tendency in CA, but not in GT. Among the platelet functions tested, only the platelet retention rate on glass beads, ADP-induced platelet aggregation and collagen-induced platelet aggregation improved in CA, each remaining unchanged in GT. In particular, collagen-induced platelet aggregation was markedly improved in the CA patient. However, the platelet adhesion to collagen (50 μg/ml)-Sepharose remained normal, both before and after the infusion of DDAVP in CA.These results suggest that an increase in the plasma vWF level and the existence of platelet membrane GPIIb/IIIa may be necessary for the improvement of primary hemostasis, after the infusion of DDAVP. The vWF-mediated platelet aggregation by collagen or ADP may produce this effect in the CA patient.

scholarly journals Properties of Calcium Sulfoaluminate Cement Mortar Modified by Hydroxyethyl Methyl Celluloses with Different Degrees of Substitution

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2136
Author(s):  
Shaokang Zhang ◽  
Ru Wang ◽  
Linglin Xu ◽  
Andreas Hecker ◽  
Horst-Michael Ludwig ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Bond Strength ◽  
Cement Mortar ◽  
Retention Rate ◽  
Methyl Cellulose ◽  
Tensile Bond Strength ◽  
Calcium Sulfoaluminate Cement ◽  
Calcium Sulfoaluminate ◽  
Cement Mortars

This paper studies the influence of hydroxyethyl methyl cellulose (HEMC) on the properties of calcium sulfoaluminate (CSA) cement mortar. In order to explore the applicability of different HEMCs in CSA cement mortars, HEMCs with higher and lower molar substitution (MS)/degree of substitution (DS) and polyacrylamide (PAAm) modification were used. At the same time, two kinds of CSA cements with different contents of ye’elimite were selected. Properties of cement mortar in fresh and hardened states were investigated, including the fluidity, consistency and water-retention rate of fresh mortar and the compressive strength, flexural strength, tensile bond strength and dry shrinkage rate of hardened mortar. The porosity and pore size distribution were also analyzed by mercury intrusion porosimetry (MIP). Results show that HEMCs improve the fresh state properties and tensile bond strength of both types of CSA cement mortars. However, the compressive strength of CSA cement mortars is greatly decreased by the addition of HEMCs, and the flexural strength is decreased slightly. The MIP measurement shows that HEMCs increase the amount of micron-level pores and the porosity. The HEMCs with different MS/DS have different effects on the improvement of tensile bond strength in different CSA cement mortars. PAAm modification can improve the tensile bond strength of HEMC-modified CSA cement mortar.

scholarly journals Phase Transition and Coefficients of Thermal Expansion in Al2−xInxW3O12 (0.2 ≤ x ≤ 1)

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4021
Author(s):  
Andrés Esteban Cerón Cerón Cortés ◽  
Anja Dosen ◽  
Victoria L. Blair ◽  
Michel B. Johnson ◽  
Mary Anne White ◽  
...  
Keyword(s):  
Phase Transition ◽  
Thermal Expansion ◽  
Thermal Shock ◽  
Monoclinic Phase ◽  
Ceramic Materials ◽  
Precipitation Method ◽  
Scanning Calorimetry ◽  
Orthorhombic Crystal ◽  
Co Precipitation

Materials from theA2M3O12 family are known for their extensive chemical versatility while preserving the polyhedral-corner-shared orthorhombic crystal system, as well as for their consequent unusual thermal expansion, varying from negative and near-zero to slightly positive. The rarest are near-zero thermal expansion materials, which are of paramount importance in thermal shock resistance applications. Ceramic materials with chemistry Al2−xInxW3O12 (x = 0.2–1.0) were synthesized using a modified reverse-strike co-precipitation method and prepared into solid specimens using traditional ceramic sintering. The resulting materials were characterized by X-ray powder diffraction (ambient and in situ high temperatures), differential scanning calorimetry and dilatometry to delineate thermal expansion, phase transitions and crystal structures. It was found that the x = 0.2 composition had the lowest thermal expansion, 1.88 × 10−6 K−1, which was still higher than the end member Al2W3O12 for the chemical series. Furthermore, the AlInW3O12 was monoclinic phase at room temperature and transformed to the orthorhombic form at ca. 200 °C, in contrast with previous reports. Interestingly, the x = 0.2, x = 0.4 and x = 0.7 materials did not exhibit the expected orthorhombic-to-monoclinic phase transition as observed for the other compositions, and hence did not follow the expected Vegard-like relationship associated with the electronegativity rule. Overall, compositions within the Al2−xInxW3O12 family should not be considered candidates for high thermal shock applications that would require near-zero thermal expansion properties.

scholarly journals Established an eco-friendly cotton fabric treating process with enhancing anti-wrinkle performance

2021 ◽  
Vol 16 ◽  
pp. 155892502110034
Author(s):  
Xiongfang Luo ◽  
Pei Cheng ◽  
Wencong Wang ◽  
Jiajia Fu ◽  
Weidong Gao
Keyword(s):  
Tensile Strength ◽  
Citric Acid ◽  
Cotton Fabric ◽  
Crosslinking Agent ◽  
Cost Effective ◽  
Waterborne Polyurethane ◽  
Cotton Fabrics ◽  
Wrinkle Resistance ◽  
Before And After ◽  
Strength Retention

This study establishes an eco-friendly anti-wrinkle treating process for cotton fabric. Sodium hydroxide-liquid ammonia pretreatment followed by 6% (w/w) PU100 adding citric acid pad-cure-dry finishing. In this process, citric acid (CA) was used as the fundamental crosslinking agent during finishing because it is a non-formaldehyde based, cost-effective and well wrinkle resistance agent. Environmental-friendly waterborne polyurethane (WPU) was used as an additive to add to the CA finishing solution. Six commercial WPUs were systematically investigated. Fabric properties like wrinkle resistance, tensile strength retention, whiteness, durable press, softness, and wettability were well investigated. Fourier transform infrared spectra and X-ray diffraction spectra were also measured and discussed before and after adding waterborne polyurethane. Tentative mechanism of the interaction among the WPU, CA, and modified cotton fabrics is provided. The effect of cotton fabric pretreatment on fabric performance was also investigated. After the eco-process’s treatment, the fabric wrinkle resistant angle was upgraded to 271 ± 7°, tensile strength retention was maintained at 66.77% ± 3.50% and CIE whiteness was elevated to 52.13 ± 3.21, which are much better than the traditional CA anti-wrinkle finishing based on mercerized cotton fabrics. This study provides useful information for textile researchers and engineers.

scholarly journals Eco-Friendly Fired Brick Produced from Industrial Ash and Natural Clay: A Study of Waste Reuse

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 877 ◽  
Author(s):  
Neslihan Doğan-Sağlamtimur ◽  
Ahmet Bilgil ◽  
Magdalena Szechyńska-Hebda ◽  
Sławomir Parzych ◽  
Marek Hebda
Keyword(s):  
Compressive Strength ◽  
Bottom Ash ◽  
Unit Weight ◽  
Waste Reuse ◽  
Industrial Solid Waste ◽  
Second Stage ◽  
Before And After ◽  
Fired Bricks ◽  
Two Stages ◽  
And Storage

Bottom ash (BA) is an industrial solid waste formed by the burning of coal. The environmental problems and storage costs caused by this waste increase with every passing day. In this study, the use of BA as an additive (clay substitute) in fired brick production was investigated. The study consisted of two stages. In the first stage, cylinder blocks were produced from clay used in brick production. The second stage was the examination of the experimental substitution of clay with 10, 20, 30 and 40% BA. Samples were fired at 900, 1000, 1100 and 1150 °C to produce fired brick samples. The unit weight, compressive strength (before and after freeze–thawing) and water absorption were analyzed for the samples. The unit weight values decreased in the samples containing BA. The mechanical properties met the conditions prescribed in the relevant standards; i.e., all of the samples fired at 1100 and 1150 °C had a sufficient compressive strength over 20 MPa. The high potential of fired bricks for the construction industry was proved. BA can be used as a clay substitute, while the developed protocol can be used to effectively produce fired bricks.

Influence of Oxygen Plasma Modification Carbon Fiber on Flexural Strength and Hydrothermal Properties of CF/PES Composite

2014 ◽  
Vol 926-930 ◽  
pp. 141-144
Author(s):  
Xu Cui ◽  
Yan Jiao Huang ◽  
Yu Gao ◽  
Shuo Wang
Keyword(s):  
Composite Material ◽  
Carbon Fiber ◽  
Flexural Strength ◽  
Plasma Treatment ◽  
Oxygen Plasma ◽  
Retention Rate ◽  
Test Method ◽  
Plasma Modification ◽  
Resin Matrix ◽  
Strength Retention

In this paper, low temperature oxygen plasma treatment method was adopted to process the carbon fiber surface. Flexural Strength test method was utilized to represent f composite material flexural strength. This paper observed flexural failure morphology of composite material by aid of SEM, then it compared the mechanical property, hygroscopicitiy and flexural strength retention rate of composite material before and after the plasma treatment. Results showed that the optimum treatment conditions of carbon fiber were 300W treatment power and 15-minute treatment time. Under the condition, the highest flexural strength value be increased by 19.55%.Saturated bibulous is low and bibulous rate is slow, flexural strength retention rate is 94.9%. And at the same time PES-C resin matrix can be strengthened, which will further improve the mechanical properties of composite materials.

Sign in / Sign up

Export Citation Format

Share Document