Fabrication of Ceramic High Temperature Microsystems

2011 ◽  
Author(s):  
Benjamin Kellie ◽  
Shaurya Prakash
Keyword(s):  
High Temperature ◽  
Weight Ratio ◽  
Polymer Binder ◽  
Binder Content ◽  
Poly Vinyl Alcohol ◽  
Heat Output ◽  
Polymeric Binder ◽  
Green Body ◽  
Cooling Rates ◽  
Heating And Cooling

This paper reports on recent advances in fabricating alumina-based ceramic microcombustors for applications in high temperature microsystems. We have fabricated alumina structures with critical dimensions on the order of 1 mm or less by using a gel-casting approach with poly(vinyl) alcohol (PVA) as a non-toxic polymeric binder. Polymer binder content, alumina weight ratio, and thermal cycling were varied systematically to develop microcombustors that can sustain stable flames in a spiral configuration allowing for better mixing of fuel and oxidizer streams for a more uniform heat output. The polymer binder and cross-linker content varied between 10 and 20% (w/v to DI water) and 50 and 100% (w/w to PVA) respectively to obtain an optimal binder content. The weight ratio of alumina (w/w 30–50%) in the binder solution was evaluated with 1.1 micron particles to observe the effect on the green body density. The green body was then fired in a high temperature furnace in air to burn-out the polymeric binder and sinter the ceramic. Heating and cooling rates, maximum operation temperature, and dwell times were evaluated to obtain high density ceramic structures with 50% or higher alumina content. Thermal stress and heating and cooling rates appear to be major parameters to control in order to obtain high-quality microcombustors.

EBSD Coupled to SEM In Situ Annealing as a Tool to Identify Recrystallization Mechanisms - Application to Zr and Ta Alloys

2012 ◽  
Vol 715-716 ◽  
pp. 486-491
Author(s):  
Nathalie Bozzolo ◽  
S. Jacomet ◽  
M. Houillon ◽  
B. Gaudout ◽  
Roland E. Logé
Keyword(s):  
High Temperature ◽  
Short Duration ◽  
Microstructure Evolution ◽  
Room Temperature ◽  
Heat Treatments ◽  
Cooling Rates ◽  
Heating And Cooling ◽  
Orientation Mapping ◽  
High Heating

A heating stage as been developed to perform in-situ annealing in a SEM equipped with an EBSD system in order to study recrystallization mechanisms. High temperature treatments could then be performed inside the SEM, up to 1180°C and with high heating-and cooling-rates (~100°C.s-1). Samples were cooled down to room temperature to perform EBSD orientation mapping in between successive short-duration heat-treatments. Microstructure evolution snapshots obtained this way are presented in this paper to show recrystallization in Zircaloy4 and in pure tantalum.

A New 1000°C Double Tilt Stage for the Hitachi 650 kV Microscope

1974 ◽  
Vol 32 ◽  
pp. 442-443
Author(s):  
W. Worthington ◽  
T. Kosel ◽  
R. Sinclair
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
High Temperature ◽  
Electric Current ◽  
Heating Element ◽  
Design Criteria ◽  
Original Design ◽  
Cooling Rates ◽  
Heating And Cooling ◽  
Specimen Holder

A new 1000°C specimen holder has been developed for the Hu-650 electron microscope and is interchangeable with other holders for the recently designed orthagonal drive tilting stage. The requirements for the high temperature device were as follows: 1. An orthogonal double-tilt stage with all original design criteria maintained(1). 2. Capability of heating standard (3mm. dia.) metallurgical specimens to 1000°C. 3. Geometry and materials should be such that stage and microscope components shall not be damaged by heat from the specimen holder. 4. The electric current to the heating element shall impart a minimum effect upon the microscope electron beam. 5. Heating and cooling rates to be as rapid as possible.

scholarly journals Ultra-High Implant Activation Efficiency In GaN Using Novel High Temperature RTP System

1998 ◽  
Vol 512 ◽  
Author(s):  
X. A. Cao ◽  
C. R. Abernathy ◽  
R. K. Singh ◽  
S. J. Pearton ◽  
M. Fu ◽  
...  
Keyword(s):  
Thin Films ◽  
Activation Energy ◽  
High Temperature ◽  
Complete Loss ◽  
Surface Degradation ◽  
Cooling Rates ◽  
Heating And Cooling ◽  
Activation Efficiency ◽  
High Heating

ABSTRACTSi+ implant activation efficiencies above 90%, even at doses of 5×1015 cm−2, have been achieved in GaN by RTP at 1400–1500°C for 10 secs. The annealing system utilizes with MoSi2 heating elements capable of operation up to 1900 °C, producing high heating and cooling rates (up to 100 °C · s−1). Unencapsulated GaN show severe surface pitting at 1300 °C, and complete loss of the film by evaporation at 1400 °C. Dissociation of nitrogen from the surface is found to occur with an approximate activation energy of 3.8 eV for GaN (compared to 4.4 eV for AIN and 3.4 eV for InN). Encapsulation with either rf-magnetron reactively sputtered or MOMBE-grown AIN thin films provide protection against GaN surface degradation up to 1400 °C, where peak electron concentrations of ∼5×1020 cm-3 can be achieved in Si-implanted GaN. SIMS profiling showed little measurable redistribution of Si, suggesting Dsi ≤ 10-13 cm2 · s−1 at 1400 °C. The implant activation efficiency decreases at higher temperatures, which may result from SiGa to SiN site switching and resultant self-compensation.

Precipitate coarsening during hot-compression testing of NiAl + 2 at.% Nb

1986 ◽  
Vol 44 ◽  
pp. 598-599
Author(s):  
W. M. Sherman ◽  
K. M. Vedula
Keyword(s):  
High Temperature ◽  
Flow Stress ◽  
Weight Ratio ◽  
Constant Strain Rate ◽  
Hot Compression ◽  
Compression Testing ◽  
Second Phase ◽  
Precipitate Coarsening ◽  
High Temperature Mechanical Properties ◽  
Ordered Intermetallic

The strength to weight ratio and oxidation resistance of NiAl make this ordered intermetallic, with some modifications, an attractive candidate to compete with many superalloys for high temperature applications. Recent studies have shown that the inherent brittleness of many polycrystalline intermetallics can be overcome by micro and macroalloying. It has also been found that the high temperature mechanical properties of NiAl can be enhanced through the addition of Nb by powder metallurgical techniques forming a dispersed second phase through interdiffusion in a polycrystalline matrix. A drop in the flow stress is observed however in a NiAl-2 at.% Nb alloy after 0.2 % strain during constant strain rate hot compression testing at 1025°C. The object of this investigation was to identify the second phase and to determine the cause of the flow stress drop.

G-E ALLOY J-1300

Alloy Digest ◽  
1959 ◽  
Vol 8 (1) ◽  
Keyword(s):  
High Temperature ◽  
Physical Properties ◽  
Precipitation Hardening ◽  
Base Alloy ◽  
Weight Ratio ◽  
Heat Treating ◽  
General Electric Company ◽  
Iron Base Alloy ◽  
Electric Company ◽  
Temperature Performance

Abstract G-E ALLOY J-1300 is a precipitation hardening iron-base alloy with an excellent strength to weight ratio. It is recommended for applications in the 1350 F. range. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance as well as forming, heat treating, machining, and joining. Filing Code: SS-83. Producer or source: General Electric Company.

POTOMAC

Alloy Digest ◽  
1975 ◽  
Vol 24 (8) ◽  
Keyword(s):  
Fracture Toughness ◽  
High Temperature ◽  
Heat Treating ◽  
General Purpose ◽  
Low Carbon ◽  
Repeated Heating ◽  
Temperature Changes ◽  
Heating And Cooling ◽  
Temperature Performance ◽  
Heat Checking

Abstract POTOMAC is a general-purpose, low-carbon, chromium-molybdenum-tungsten hot-work steel. It has excellent resistance to shock and heat checking after repeated heating and cooling. Potomac is suitable for hot-work applications involving severe conditions of shock and sudden temperature changes. This datasheet provides information on composition, physical properties, hardness, and tensile properties as well as fracture toughness. It also includes information on high temperature performance as well as forming, heat treating, and machining. Filing Code: TS-290. Producer or source: Allegheny Ludlum Corporation.

Texture Evolution Under Fast Heating and Cooling Rates of Zirconium Alloys Studied In-Situ by Synchrotron X-Ray Diffraction

2020 ◽  
Author(s):  
Chi-Toan Nguyen ◽  
Alistair Garner ◽  
Javier Romero ◽  
Antoine Ambard ◽  
Michael Preuss ◽  
...  
Keyword(s):  
Texture Evolution ◽  
Zirconium Alloys ◽  
X Ray Diffraction ◽  
Fast Heating ◽  
Cooling Rates ◽  
X Ray ◽  
Heating And Cooling

scholarly journals Laboratory-Scale Processing and Performance Assessment of Ti–Ta High-Temperature Shape Memory Spring Actuators

2021 ◽  
Author(s):  
A. Paulsen ◽  
H. Dumlu ◽  
D. Piorunek ◽  
D. Langenkämper ◽  
J. Frenzel ◽  
...  
Keyword(s):  
High Temperature ◽  
Shape Memory ◽  
Detrimental Effect ◽  
Wire Drawing ◽  
Fast Heating ◽  
Heating And Cooling ◽  
Arc Melting ◽  
Ω Phase ◽  
And Performance

AbstractTi75Ta25 high-temperature shape memory alloys exhibit a number of features which make it difficult to use them as spring actuators. These include the high melting point of Ta (close to 3000 °C), the affinity of Ti to oxygen which leads to the formation of brittle α-case layers and the tendency to precipitate the ω-phase, which suppresses the martensitic transformation. The present work represents a case study which shows how one can overcome these issues and manufacture high quality Ti75Ta25 tensile spring actuators. The work focusses on processing (arc melting, arc welding, wire drawing, surface treatments and actuator spring geometry setting) and on cyclic actuator testing. It is shown how one can minimize the detrimental effect of ω-phase formation and ensure stable high-temperature actuation by fast heating and cooling and by intermediate rejuvenation anneals. The results are discussed on the basis of fundamental Ti–Ta metallurgy and in the light of Ni–Ti spring actuator performance.

scholarly journals Integrated high temperature heat pumps and thermal storage tanks for combined heating and cooling in the industry

2021 ◽  
Vol 189 ◽  
pp. 116731
Author(s):  
Marcel Ulrich Ahrens ◽  
Sverre Stefanussen Foslie ◽  
Ole Marius Moen ◽  
Michael Bantle ◽  
Trygve Magne Eikevik
Keyword(s):  
High Temperature ◽  
Thermal Storage ◽  
Heat Pumps ◽  
Storage Tanks ◽  
Heating And Cooling ◽  
Temperature Heat
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