In Situ Visualization Measurement of Flat Plate Ablation in High-Temperature Gas Flow

2018 ◽  
Vol 85 (6) ◽  
Author(s):  
Zhe Qu ◽  
Xian Wang ◽  
Yunlong Tang ◽  
Honghong Su ◽  
Lianzhong Chen ◽  
...  
Keyword(s):  
Flat Plate ◽  
Thermal Ablation ◽  
Gas Flow ◽  
Feature Detection ◽  
Thermal Protection ◽  
Experimental Results ◽  
Image Feature ◽  
In Situ Observation ◽  
Optoelectronic System

In this work, we develop an optoelectronic system for in situ observation and measurement in hypervelocity flows. The system has the advantages of strong radiation resistance and self-adaptive exposure time of the cameras. Thermal ablation test using flat plate thermal protection system material was carried out in an arc jet. Real-time ablation images were captured and analyzed to understand the thermal ablation mechanism. Through the modified algorithms of particle image velocity (PIV) and image feature detection, the surface recession rate and the velocity distribution of the melted droplets flowing on the sample surface were obtained. The experimental results demonstrate vast potential for using this in situ measuring technique in various engineering applications. Finally, the formation and merging of the melted droplets was analyzed based on energy theory, and the numerical simulation results showed good agreement with the actual experimental results.

In-Situ Measurement and Monitoring of Fiber Preform Permeability for Liquid Composite Molding

2000 ◽  
Author(s):  
Zhiyong Liang ◽  
Chuck Zhang ◽  
Ben Wang ◽  
Chiang Shih
Keyword(s):  
Gas Flow ◽  
Gas Permeability ◽  
Pressure Profile ◽  
Air Permeability ◽  
Experimental Results ◽  
Liquid Composite Molding ◽  
Permeability Measurement ◽  
Fiber Preform ◽  
Composite Molding

Abstract In a liquid composite molding (LCM) process such as resin transfer molding (RTM), quality control depends on an in-situ permeability profile of the fibrous preform taken just before resin injection. However, the conventional permeability measurement method, which uses liquid (oil or resin) as its working fluid, only measures the average preform permeability in an off-line mode. It cannot be used to create an in-situ permeability profile because of fiber pollution, and cannot be used to reveal local permeability variations of preform. This study develops a new permeability characterization method that uses gas flow and pressure profiles to measure preform permeability variation in a closed mold assembly. This method is based upon two research findings: (1) that the air permeability of a preform can be obtained through measuring the pressure profile of gas flow, and (2) that resin permeability is highly correlated with air permeability for the same fiber preform. In this paper, the validity of this method is discussed. Experimental results of gas permeability measurement with defective and defect-free preforms are presented, and quantitative models for correlation of gas permeability versus pressure profile and of gas permeability versus resin permeability are also provided. Finally, the efficacy of the proposed method is illustrated through experimental results.

In-Situ Observation of UV/Ozone Oxidation of Silicon using Spectroscopic Eli Psometry

1999 ◽  
Vol 569 ◽  
Author(s):  
T. Saitoh ◽  
D. Kobayashi ◽  
D. Kimura ◽  
K. Asai
Keyword(s):  
Gas Flow ◽  
Uv Light ◽  
Silicon Surfaces ◽  
In Situ Observation ◽  
Electric Field Effect ◽  
Initial Oxidation ◽  
Oxidation Rates ◽  
Almost All ◽  
Uv Ozone

ABSTRACTInitial oxidation process of silicon in UV/ozone ambient has been monitored using a multi-wavelength, in-situ spectroscopic ellipsometry. Ozone gas was chemically formed by photochemical reaction of oxygen under ulUmviolet illuimination. The oxide growth was monitored for hydrogenated silicon surfaces as functions of oxygen gas flow rate, gas pressure and wafer temperature. Initial oxidation rates were very high at almost all the temperatures. The oxidation rate was 0.2 nm/min about ten times higher than that for thermal oxidation without UV light at low temperatures. The accelerated oxidation was probably due to an electric field effect on the oxidation of back-bond silicon by active oxygen atoms included in the ozone gas.

scholarly journals Preparation, Characterization and Tribological Properties of Diamond-Like Carbon Film on AZ31 Magnesium Alloy

2019 ◽  
Vol 804 ◽  
pp. 69-74
Author(s):  
Bei Bei Han ◽  
Dong Ying Ju ◽  
Susumu Sato ◽  
Hui Jun Zhao
Keyword(s):  
Tribological Properties ◽  
Gas Flow ◽  
Carbon Film ◽  
Observation System ◽  
In Situ Observation ◽  
Force Measurements ◽  
Maximum Hardness ◽  
Low Friction ◽  
Dlc Coatings

In this study, DLC films were deposited using IBED with various CH4/H2 ratio, gas flow rates and accelerating voltages. The composition and mechanical properties of the DLC coatings were characterized using SEM, Raman spectroscopy and nanoindentor. The tribological properties of the coating were also investigated using a frictional surface microscope with an in situ observation system and friction force measurements. The DLC films were characterized by a lower ID/IG, higher hardness, and improved tribological properties when deposited at a lower accelerating voltage (6 kV). At the CH4/H2 ratio of 1:99 and 6 sccm/6 kV, minimum ID/IG values of 0.62, relatively low friction coefficient of 0.12 , and a maximum hardness of 4056 HV were attained respectively.

Parameters Influencing the Secondary Hydrogenation of Zr-Sn and Zr-Nb Alloys During Steam Oxidation Under LOCA and Severe Accident Conditions

2010 ◽  
Author(s):  
Mirco K. Grosse ◽  
Martin Steinbrueck ◽  
Juri Stuckert
Keyword(s):  
Oxide Layer ◽  
Large Scale ◽  
Gas Flow ◽  
Hydrogen Diffusion ◽  
Neutron Radiography ◽  
Hydrogen Uptake ◽  
Experimental Results ◽  
Steam Oxidation ◽  
Severe Accident

The parameters influencing secondary hydrogen uptake can be divided into two groups: material properties and process parameters. The first group includes for instance the steam oxidation kinetics, the oxide morphology and the hydrogen diffusion through the oxide layer. The second group covers for instance the temperature, the total pressure, the gas flow type and rates, the cladding area and the filling of the rods. Together with a theoretical view on the influence of different parameters on the hydrogen uptake of zirconium alloys experimental results from separate-effect tests, large-scale QUENCH tests and in-situ neutron radiography investigations of the hydrogen uptake during steam oxidation will be presented. The hydrogen concentrations in specimens made from commonly used cladding materials were determined by quantitative analysis of neutron radiographs. Information obtained from ex- and in-situ steam oxidation experiments will be given. The presentation of the experimental results will be focused on the influence of oxidation time and temperature, of the oxide layer morphology, the sample geometry and of the gas flow rates on the hydrogen concentration of the remaining metal phases. Differences between Zr-Sn, Zr-Nb and Zr-Sn-Nb alloys will be discussed.

In Situ Observation of Catalyzed Gasification of Graphite by Nickel

1981 ◽  
Vol 39 ◽  
pp. 76-77
Author(s):  
R. T. K. Baker ◽  
R. D. Sherwood
Keyword(s):  
Objective Lens ◽  
In Situ Observation ◽  
Gas Flows ◽  
Catalytic Gasification ◽  
Television Camera ◽  
Viewing Screen ◽  
Fuels And Chemicals ◽  
Gasification Of Carbon ◽  
Transmission Microscope

The catalytic gasification of carbon at high temperature by microscopic size metal particles is of fundamental importance to removal of coke deposits and conversion of refractory hydrocarbons into fuels and chemicals. The reaction of metal/carbon/gas systems can be observed by controlled atmosphere electron microscopy (CAEM) in an 100 KV conventional transmission microscope. In the JEOL gas reaction stage model AGl (Fig. 1) the specimen is positioned over a hole, 200μm diameter, in a platinum heater strip, and is interposed between two apertures, 75μm diameter. The control gas flows across the specimen and exits through these apertures into the specimen chamber. The gas is further confined by two apertures, one in the condenser and one in the objective lens pole pieces, and removed by an auxiliary vacuum pump. The reaction zone is <1 mm thick and is maintained at gas pressure up to 400 Torr and temperature up to 1300<C as measured by a Pt-Pt/Rh 13% thermocouple. Reaction events are observed and recorded on videotape by using a Philips phosphor-television camera located below a hole in the center of the viewing screen. The overall resolution is greater than 2.5 nm.

In situ observation of the martensitic transformation in (Mg,Y)-PSZ

1986 ◽  
Vol 44 ◽  
pp. 500-501
Author(s):  
R-R. Lee
Keyword(s):  
Martensitic Transformation ◽  
High Strength ◽  
Nucleation And Growth ◽  
In Situ Observation ◽  
Considerable Potential ◽  
Transmission Electron ◽  
Structural Applications ◽  
Applied Stresses ◽  
Kinetics Of

Partially-stabilized ZrO2 (PSZ) ceramics have considerable potential for advanced structural applications because of their high strength and toughness. These properties derive from small tetragonal ZrO2 (t-ZrO2) precipitates in a cubic (c) ZrO2 matrix, which transform martensitically to monoclinic (m) symmetry under applied stresses. The kinetics of the martensitic transformation is believed to be nucleation controlled and the nucleation is always stress induced. In situ observation of the martensitic transformation using transmission electron microscopy provides considerable information about the nucleation and growth aspects of the transformation.

In situ TEM observations of melting in nanosized eutectic Pb-Cd inclusions embedded in Al

1996 ◽  
Vol 54 ◽  
pp. 986-987
Author(s):  
S. Hagège ◽  
U. Dahmen ◽  
E. Johnson ◽  
A. Johansen ◽  
V.S. Tuboltsev
Keyword(s):  
Electron Microscope ◽  
Melt Spinning ◽  
Ternary Alloys ◽  
Solid Matrix ◽  
Eutectic System ◽  
In Situ Tem ◽  
In Situ Observation ◽  
Orientation Relationships ◽  
Transmission Electron

Small particles of a low-melting phase embedded in a solid matrix with a higher melting point offer the possibility of studying the mechanisms of melting and solidification directly by in-situ observation in a transmission electron microscope. Previous studies of Pb, Cd and other low-melting inclusions embedded in an Al matrix have shown well-defined orientation relationships, strongly faceted shapes, and an unusual size-dependent superheating before melting.[e.g. 1,2].In the present study we have examined the shapes and thermal behavior of eutectic Pb-Cd inclusions in Al. Pb and Cd form a simple eutectic system with each other, but both elements are insoluble in solid Al. Ternary alloys of Al (Pb,Cd) were prepared from high purity elements by melt spinning or by sequential ion implantation of the two alloying additions to achieve a total alloying addition of up to lat%. TEM observations were made using a heating stage in a 200kV electron microscope equipped with a video system for recording dynamic behavior.

In-Situ Observation of Clay Minerals Hydrated and Intercalated With Liquid Chemicals Using Film-Sealed Environmental Cell

1980 ◽  
Vol 38 ◽  
pp. 208-209 ◽  
Author(s):  
K. Fukushima ◽  
N. Kohyama ◽  
A. Fukami
Keyword(s):  
Carbon Film ◽  
Resolving Power ◽  
In Situ Observation ◽  
Interlayer Water ◽  
Saturated Water ◽  
Structure Changes ◽  
Environmental Cell ◽  
Gas Layer ◽  
20 Nm

A film-sealed high resolution environmental cell(E.C) for observing hydrated materials had been developed by us(l). Main specification of the E.C. is as follows: 1) Accelerated voltage; 100 kV. 2) Gas in the E.C.; saturated water vapour with carrier gas of 50 Torr. 3) Thickness of gas layer; 50 μm. 4) Sealing film; evaporated carbon film(20 nm thick) with plastic microgrid. 5) Resolving power; 1 nm. 6) Transmittance of electron beam; 60% at 100 kV. The E.C. had been successfully applied to the study of hydrated halloysite(2) (3). Kaolin minerals have no interlayer water and are basically non-expandable but form intercalation compounds with some specific chemicals such as hydrazine, formamide and etc. Because of these compounds being mostly changed in vacuum, we tried to reveal the structure changes between in wet air and in vacuum of kaolin minerals intercalated with hydrazine and of hydrated state of montmori1lonite using the E.C. developed by us.

Development of Highly Precise Cell Stretching Microdevice and in-situ Observation of Stretched Cell

2013 ◽  
Vol 133 (12) ◽  
pp. 350-357
Author(s):  
Yuta Nakashima ◽  
Ryo Monji ◽  
Katsuya Sato ◽  
Kazuyuki Minami
Keyword(s):  
In Situ Observation ◽  
Cell Stretching

In-situ automatic observations of ice thickness of seas

2012 ◽  
Vol 19 (3) ◽  
pp. 583-592 ◽  
Author(s):  
Yinke Dou ◽  
Xiaomin Chang
Keyword(s):  
Sea Ice ◽  
New Technologies ◽  
Capacitive Sensor ◽  
Automatic Monitoring ◽  
Ice Thickness ◽  
In Situ Observation ◽  
Glacier Surface ◽  
Sea Ice Thickness ◽  
Surface Ice

Abstract Ice thickness is one of the most critical physical indicators in the ice science and engineering. It is therefore very necessary to develop in-situ automatic observation technologies of ice thickness. This paper proposes the principle of three new technologies of in-situ automatic observations of sea ice thickness and provides the findings of laboratory applications. The results show that the in-situ observation accuracy of the monitor apparatus based on the Magnetostrictive Delay Line (MDL) principle can reach ±2 mm, which has solved the “bottleneck” problem of restricting the fine development of a sea ice thermodynamic model, and the resistance accuracy of monitor apparatus with temperature gradient can reach the centimeter level and research the ice and snow substance balance by automatically measuring the glacier surface ice and snow change. The measurement accuracy of the capacitive sensor for ice thickness can also reach ±4 mm and the capacitive sensor is of the potential for automatic monitoring the water level under the ice and the ice formation and development process in water. Such three new technologies can meet different needs of fixed-point ice thickness observation and realize the simultaneous measurement in order to accurately judge the ice thickness.

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