scholarly journals Performance of CVD and CVR Coated Carbon-Carbon in High Temperature Hydrogen

1993 ◽  
Vol 327 ◽  
Author(s):  
J. W. Adams ◽  
R. E. Barlettia ◽  
J. Svandrlik ◽  
P. E. Vanier
Keyword(s):  
Development Process ◽  
Chemical Vapor ◽  
Screening Tests ◽  
Carbon Structure ◽  
Carbon Substrates ◽  
Component Development ◽  
Flowing Hydrogen ◽  
Deposition Processes ◽  
Particle Bed ◽  
Coated Carbon

AbstractAs a part of the component development process for the particle bed reactor (PBR), it is necessary to develop coatings which will be time and temperature stable at extremely high temperatures in flowing hydrogen. These coatings must protect the underlying carbon structure from attack by the hydrogen coolant. Degradation which causes small changes in the reactor component, e.g. hole diameter in the hot frit, can have a profound effect on operation. The ability of a component to withstand repeated temperature cycles is also a coating development issue. Coatings which crack or spall under these conditions would be unacceptable. While refractory carbides appear to be the coating material of choice for carbon substrates being used in PBR components, the method of applying these coatings can have a large effect on their performance. Two deposition processes for these refractory carbides, chemical vapor deposition (CVD) and chemical vapor reaction (CVR) have been evaluated.Screening tests for these coatings consisted of testing of coated 2-D and 3-D weave carbon-carbon in flowing hot hydrogen at one atmosphere. Carbon loss from these samples was measured as a function of time. Exposure temperatures up to 3000 K were used and samples were exposed in a cyclical fashion, cooling to room temperature between exposures. The results of these measurements are presented along with an evaluation of the relative merits of CVR and CVD coatings for this application.

Performance of CVR Coatings for PBR Fuels

1993 ◽  
Vol 327 ◽  
Author(s):  
Jay W. Adams ◽  
R. E. Barletta ◽  
J. Svandrlik ◽  
P. E. Vanier
Keyword(s):  
Pyrolytic Graphite ◽  
Chemical Vapor ◽  
Screening Tests ◽  
Coated Materials ◽  
Before And After ◽  
Component Development ◽  
Flowing Hydrogen ◽  
Fuel Particles ◽  
Particle Bed ◽  
Surrogate Fuel

AbstractAs a part of the component development process for the particle bed reactor (PBR), it is necessary to develop coatings for fuel particles which will be time and temperature stable. These coatings must not only protect the particle from attack by the hydrogen coolant, but must also help to maintain the bed in a coolable geometry and mitigate against fission product release. In order to develop these advanced coatings, a process to produce chemical vapor reaction (CVR) coatings on fuel for PBRs has been developed.The initial screening tests for these coatings consisted of testing in flowing hot hydrogen at one atmosphere. Surrogate fuel particles consisting of pyrolytic graphite coated graphite particles have been heated in flowing hydrogen at constant temperature. The carbon loss from these particles was measured as a function of time. Exposure temperatures ranging from 2500 to 3000 K were used and samples were exposed for up to 14 minutes in a cyclical fashion, cooling to room temperature between exposures. The rate of weight loss measured as a function of time is compared to that from other tests of coated materials under similar conditions. Microscopic examination of the coatings before and after exposure was also conducted and these results are presented.

scholarly journals Characterization of Thin Chromium Coatings Produced by PVD Sputtering for Optical Applications

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 215
Author(s):  
Andreia A. Ferreira ◽  
Francisco J. G. Silva ◽  
Arnaldo G. Pinto ◽  
Vitor F. C. Sousa
Keyword(s):  
Automotive Industry ◽  
Vapor Deposition ◽  
Physical Vapor Deposition ◽  
Early Stage ◽  
Chemical Vapor ◽  
Experimental Tests ◽  
Scratch Test ◽  
Industrial Sectors ◽  
Deposition Processes ◽  
Optical Applications

PVD (physical vapor deposition) and CVD (chemical vapor deposition) have gained greater significance in the last two decades with the mandatory shift from electrodeposition processes to clean deposition processes due to environmental, public safety, and health concerns. Due to the frequent use of coatings in several industrial sectors, the importance of studying the chromium coating processes through PVD–sputtering can be realized, investing in a real alternative to electroplated hexavalent chromium, usually denominated by chromium 6, regularly applied in electrodeposition processes of optical products in the automotive industry. At an early stage, experimental tests were carried out to understand which parameters are most suitable for obtaining chromium coatings with optical properties. To study the coating in a broad way, thickness and roughness analysis of the coatings obtained using SEM and AFM, adhesion analyzes with the scratch-test and transmittance by spectrophotometry were carried out. It was possible to determine that the roughness and transmittance decreased with the increase in the number of layers, the thickness of the coating increased linearly, and the adhesion and resistance to climatic tests remained positive throughout the study. Thus, this study allows for the understanding that thin multilayered Cr coatings can be applied successfully to polymeric substrates regarding optical applications in the automotive industry.

Pre-Cracking and Plasma Enhanced Metalorganic Chemical Vapor Deposition Processes for Epitaxial Hg1−xCdxTe and HgTe-CdTe Superlattice Growth

1987 ◽  
Vol 102 ◽  
Author(s):  
P.-Y. Lu ◽  
L. M. Williams ◽  
C.-H. Wang ◽  
S. N. G. Chu ◽  
M. H. Ross
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Metalorganic Chemical Vapor Deposition ◽  
Chemical Vapor ◽  
Infrared Transmission ◽  
Chemical Vapor Deposition Growth ◽  
Deposition Processes ◽  
Cdznte Substrates ◽  
First Time ◽  
Metalorganic Chemical

ABSTRACTTwo low temperature metalorganic chemical vapor deposition growth techniques, the pre-cracking method and the plasma enhanced method, will be discussed. The pre-cracking technique enables one to grow high quality epitaxial Hg1−xCdxTe on CdTe or CdZnTe substrates at temperatures around 200–250°C. HgTe-CdTe superlattices with sharp interfaces have also been fabricated. Furthermore, for the first time, we have demonstrated that ternary Hg1−xCdTe compounds and HgTe-CdTe superlattices can be successfully grown by the plasma enhanced process at temperatures as low as 135 to 150°C. Material properties such as surface morphology, infrared transmission, Hall mobility, and interface sharpness will be presented.

Goal-Oriented Machine Learning-Based Component Development Process

2021 ◽  
Author(s):  
Jati H. Husen ◽  
Hnin Thandar Tun ◽  
Nobukazu Yoshioka ◽  
Hironori Washizaki ◽  
Yoshiaki Fukazawa
Keyword(s):  
Machine Learning ◽  
Development Process ◽  
Component Development
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