Influence of Pulse Frequency on Mullite Coatings Prepared by Pulse Arc Discharge Deposition Process and Activation Energy

2014 ◽  
Vol 809-810 ◽  
pp. 635-641
Author(s):  
Bo Zhang ◽  
Jian Feng Huang ◽  
Cui Yan Li ◽  
Li Yun Cao ◽  
Hai Bo Ouyang ◽  
...  
Keyword(s):  
Activation Energy ◽  
Arc Discharge ◽  
Deposition Process ◽  
Pulse Frequency ◽  
Deposition Kinetics ◽  
Mullite Phase ◽  
Mullite Coatings ◽  
Sic Composites ◽  
Mullite Powder ◽  
Source Materials

Mullite coatings were prepared on C/C-SiC composites surface by pulse arc discharge deposition using mullite powder as source materials. Phase composites and microstructures of the as-prepared mullite coatings were characterized by XRD and SEM. Deposition kinetics and influence of pulse frequency on the phase composites and microstructures were investigated. The results indicate that the outer layer is composed of mullite phase, density and homogeneity of the mullite coatings are achieved when the pulse frequency reaches 2000 Hz. The deposition amount of the mullite coatings also increases with increasing deposition temperature. The deposition mass of the coatings and the square root of the deposition time at different deposition temperatures according to linear relationship, and the deposition activation energy is calculated to be 32.24 kJ/mol.

Effect of particle size on anti-oxidation property of mullite coating prepared by pulse arc discharge deposition

RSC Advances ◽  
2015 ◽  
Vol 5 (125) ◽  
pp. 103744-103751
Author(s):  
Huang Jianfeng ◽  
Zhang Bo ◽  
OuYang Haibo ◽  
Cao Liyun ◽  
Li Cuiyan ◽  
...  
Keyword(s):  
Particle Size ◽  
Arc Discharge ◽  
Particle Sizes ◽  
Mullite Coating ◽  
Mullite Coatings ◽  
Effect Of Particle Size ◽  
Sic Composites

Mullite coatings with different particle sizes were prepared on carbon/carbon (C/C)–SiC composites surface by pulse arc discharge deposition (PADD).

A Computational Fluid Dynamics and Chemistry Model for Jet Fuel Thermal Stability

1992 ◽  
Vol 114 (1) ◽  
pp. 104-110 ◽  
Author(s):  
J. L. Krazinski ◽  
S. P. Vanka ◽  
J. A. Pearce ◽  
W. M. Roquemore
Keyword(s):  
Fluid Dynamics ◽  
Activation Energy ◽  
Computational Fluid Dynamics ◽  
Dissolved Oxygen ◽  
Deposition Process ◽  
Decomposition Reaction ◽  
Heated Tube ◽  
Precursor Decomposition ◽  
Autoxidation Reaction ◽  
Decomposition Chemistry

This paper describes the development of a model for predicting the thermal decomposition rates of aviation fuels. A thermal deposition model was incorporated into FLANELS-2D, an existing computational fluid dynamics (CFD) code that solves the Reynolds-averaged conservation equations of mass, momentum, and energy. The decomposition chemistry is modeled by three global Arrhenius expressions in which the fuel decomposition was assumed to be due to an autoxidation reaction with dissolved oxygen. The deposition process was modeled by assuming that all deposit-forming species transported to the wall adhered and formed a deposit. Calibration of the model required the determination of the following parameters for a given fuel: (1) the pre-exponential constant and activation energy for the wall reaction, (2) the pre-exponential constant and activation energy for the bulk autoxidation reaction, and (3) the pre-exponential constant and activation energy for the precursor decomposition reaction. Values for these parameters were estimated using experimental data from published heated-tube experiments. Results show that the FLANELS-2D code performed well in estimating the fuel temperatures and that the three-equation chemistry model performed reasonably well in accounting for both the rate of deposition and the amount of dissolved oxygen present in the fuel at the end of the heated tube.

Improving of Energy Density in Welding Arc and its Mechanism Study

2013 ◽  
Vol 711 ◽  
pp. 229-234 ◽  
Author(s):  
Tian Jiao Xiao ◽  
Yong Lun Song ◽  
Qiu Shi Hu ◽  
Chao Li
Keyword(s):  
Energy Density ◽  
Arc Discharge ◽  
Pulse Frequency ◽  
Inert Gas ◽  
Input Energy ◽  
Mechanism Study ◽  
Pulse Input ◽  
Welding Arc ◽  
Ionization Region ◽  
Contraction Effect

As to traditional single electrode free welding arc, changes about energy density of the ionizing region in the center of arc column is not obvious with current increases due to structural limitations. In this paper, we developed parallel multi-electrode arc discharge torch which is based on the mechanism of self-magnetic contraction effect in welding arc, the torch effectively improve energy density of ionization region in non-melting inert gas arc, which is proved by experiments, and we discussed, effect of the pulse input energy and pulse frequency to energy density of the arc with parallel multi-electrode torch. This study demonstrated the approach of improving the energy density of arc ionizing region by self-magnetic pinch effect is feasible.

Fabrication and Properties of Porous Anorthite⁄Mullite Ceramics

2012 ◽  
Vol 512-515 ◽  
pp. 590-595 ◽  
Author(s):  
Ya Mei Lin ◽  
Cui Wei Li ◽  
Feng Kun Yang ◽  
Chang An Wang
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Open Porosity ◽  
Raw Material ◽  
Composite Ceramics ◽  
Porous Composite ◽  
Mullite Phase ◽  
Powder Content ◽  
Mullite Powder ◽  
Mullite Ceramics

Porous anorthite/mullite composite ceramics with different mullite content were fabricated by foam-gelcasting, using CaCO3, SiO2, α-Al2O3as raw material for anorthite phase and mullite powder for mullite phase. Effects of mullite powder content on bulk density, porosity, compressive strength and thermal conductivity of the porous composite ceramics were researched. It has been shown that mullite powder content has great effect on microstructure and properties of the porous anorthite⁄mullite composite ceramics. The open porosity of the prepared porous anorthite⁄mullite composite ceramics is in the range of 58.7 %~77.5 %, the compressive strength is between 4.2 and 30.9 MPa, and the thermal conductivity is in the range of 0.18 ~1.47 W⁄(m·K).

Preparation of Hydroxyapatite Coatings on Carbon/Carbon Composites by a Hydrothermal Electrodeposition Process

2008 ◽  
Vol 368-372 ◽  
pp. 1238-1240
Author(s):  
Guang Yan Zhu ◽  
Jian Feng Huang ◽  
Li Yun Cao ◽  
Min Zhou ◽  
Jian Peng Wu
Keyword(s):  
Activation Energy ◽  
Deposition Rate ◽  
Carbon Composites ◽  
Hydrothermal Temperature ◽  
Electrodeposition Process ◽  
Deposition Kinetics ◽  
Electrodeposition Method ◽  
Hydroxyapatite Coatings ◽  
Surface Microstructures ◽  
Sem Analyses

Hydroxyapatite (HAp) coatings were prepared by a hydrothermal electrodeposition method on Carbon/carbon (C/C) composites. The as-prepared HAp coatings were characterized by XRD and SEM analyses. The influence of hydrothermal temperature on the phase and surface microstructures of HAp coatings and the corresponding deposition kinetics were particularly investigated. Results show that with the increase of hydrothermal temperature, the crystallinity, density and homogenous of the prepared HAp coatings are improved. The deposition rate also increases with the increase of hydrothermal temperature. The deposition activation energy of HAp coatings by the hydrothermal electrodeposition process is calculated to be 25.89 kJ/mol.

scholarly journals Electroless Ni–P Plating on Mullite Powders and Study of the Mechanical Properties of Its Plasma-Sprayed Coating

Coatings ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 18
Author(s):  
Kaiwang Chen ◽  
Penglin Zhang ◽  
Pengfei Sun ◽  
Xianming Niu ◽  
Chunlian Hu
Keyword(s):  
Amorphous Layer ◽  
Cell Structures ◽  
Mullite Coating ◽  
Lower Porosity ◽  
Mullite Coatings ◽  
Sprayed Coating ◽  
Plasma Sprayed ◽  
Steel Substrates ◽  
Mullite Powder ◽  
Original Coating

To effectively improve the properties of a mullite coating and its interfacial bonding with the substrate, a Ni–P layer is deposited on the surface of mullite powders by electroless plating. The original mullite powders and coated mullite powders are then deposited onto stainless-steel substrates by plasma spraying. The growth mechanism of the Ni–P layer during the plating, the microstructures of the coated powders and mullite coating and the properties of the mullite coatings are characterized and analyzed. The results indicate that the Ni–P layer on the surface of the mullite powder has cell structures with a dense uniform distribution and grows in layers on the surface of the mullite powder. The crystallization behavior of Ni-P amorphous layer is induced by heat treatment. Compared to the original mullite coating, the coating prepared by the coated mullite powders has better manufacturability, stronger adhesion to the substrate, lower porosity (7.40%, 65% of that of the original coating), higher hardness (500.1 HV, 1.2 times that of the original coating), and better thermal cycle resistance (two times that of the original coating). The method of preparation of high-temperature thermal barrier coatings with coated mullite powders has a high application value.

scholarly journals Deposition Process Using a Shunting Arc Discharge

2008 ◽  
Vol 51 (2) ◽  
pp. 75-80
Author(s):  
Koichi TAKAKI ◽  
Ken YUKIMURA
Keyword(s):  
Arc Discharge ◽  
Deposition Process

Synthesis, morphology, and formation mechanism of mullite particles produced by ultrasonic spray pyrolysis

1996 ◽  
Vol 11 (7) ◽  
pp. 1706-1716 ◽  
Author(s):  
Dj. Janaćković ◽  
V. Jokanović ◽  
Lj. Kostić-Gvozdenović ◽  
Lj. Živković ◽  
D. Uskoković
Keyword(s):  
Spray Pyrolysis ◽  
Silicic Acid ◽  
Formation Mechanism ◽  
Ultrasonic Spray Pyrolysis ◽  
Spherical Particles ◽  
Mullite Phase ◽  
Ultrasonic Spray ◽  
Solution Preparation ◽  
Subsequent Phase ◽  
Mullite Powder

Submicrometer spherical particles of mullite powder were synthesized by ultrasonic spray pyrolysis of emulsion and solutions, using tetra-ethyl-orthosilicate (TEOS) or silicic-acid and Al(NO3)3 · 9H2O as initial compounds. Crystallization of mullite phase was determined by differential thermal (DT), thermogravimetric (TG), infrared (IR), and x-ray analyses. The synthesis of mullite from TEOS emulsion occurs by crystallization of γ–Al2O3 (or Al, Si-spinel) from the amorphous phase and its subsequent reaction with amorphous SiO2, as well as by crystallization of pseudotetragonal mullite below 1000 °C and its subsequent phase transformation into orthorhombic mullite. In the powders produced from silicic acid solutions, synthesis of mullite occurs only by crystallization of γ–Al2O3 between 900 and 1000 °C and its further reaction with amorphous SiO2 between 1100 and 1200 °C. Particle formation mechanism depended directly on the initial emulsion or solution preparation, i.e., on the phase separation in the emulsion and on the silicic-acid crosslinking conditions.

Preparation of Cf/SiC Composites by Chemical Liquid-Vapor Deposition Process

2012 ◽  
Vol 512-515 ◽  
pp. 804-807
Author(s):  
Min Mei ◽  
Xin Bo He ◽  
Xuan Hui Qu ◽  
Hai Feng Hu ◽  
Yu Di Zhang ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Vapor Deposition ◽  
Fracture Behavior ◽  
Deposition Process ◽  
Xrd Pattern ◽  
Sic Ceramics ◽  
The Matrix ◽  
Sic Composites ◽  
Load Deflection Curve ◽  
Liquid Vapor

The conversion of the liquid polycabosilane (LPCS) into silicon carbide was investigated by IR, XRD, which indicated the feasibility of the transition from LPCS to SiC ceramics above 900°C. The FTIR spectra and XRD Pattern of the Cf/SiC composites show that the matrix deposited at 1200°C has silicon carbide structure with the crystallite size of β-SiC phase of about 41 nm, while the SiC phase is amorphous at 900°C. The carbon fiber reinforced silicon carbide composites (Cf/SiC) were hereby prepared at 900°C and 1200°C, through chemical liquid-vapor deposition (CLVD) process using LPCS as precursor. Flexural strength of 224 MPa for Cf/SiC specimen with density of 1.81g·cm-3was obtained after being prepared at 1200°C for 30 minutes. The load-deflection curve has shown that the fracture behavior of the Cf/SiC composites is a typical non-brittleness. The results indicate that the CLVD process has a great advantage and prospect to prepare Cf/SiC composites in future.

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