Ultrasonic In-Situ Monitoring of Aluminum Alloy During Solidification and Melting

2004 ◽  
Author(s):  
Ikuo Ihara ◽  
Dikky Burhan ◽  
Yoshihisa Seda
Keyword(s):  
Aluminum Alloy ◽  
Molten Aluminum ◽  
Cooling System ◽  
Longitudinal Velocity ◽  
Solidification Process ◽  
Outer Wall ◽  
Ultrasonic Sensor ◽  
In Situ Monitoring ◽  
Long Time

In both research and production involving solidification of materials, it would be beneficial to have an in-situ, real-time characterization of the material properties during solidification process. In this work ultrasonic in-situ monitoring of aluminum alloy (Al-12.6%Si) during solidification and melting using a high temperature ultrasonic sensor is presented. The ultrasonic sensor used mainly consists of a conventional piezoelectric transducer, a titanium buffer rod as an acoustic waveguide and a cooling system. A steel reflector is assembled at the probing end of the sensor to make time-of-flight measurements. The sustainability of the sensor has been evaluated for long time immersion up to 16 hours in the molten aluminum alloy and the possible reaction at the outer wall of the titanium rod has been examined. It has been demonstrated that the titanium buffer rod has good wettability and sustainability to molten aluminum. Using the ultrasonic sensor, pulse echo measurements with the aluminum alloy have been performed in temperature range from 200 to 800 °C. The changes of the longitudinal velocity of the aluminum alloy during solidification and melting processes have been successfully monitored. In addition the change in the amplitude of reflected echoes during solidification is discussed.

Heteroepitaxy of GaN on Silicon: In Situ Measurements

2005 ◽  
Vol 483-485 ◽  
pp. 1051-1056
Author(s):  
A. Krost ◽  
Armin Dadgar ◽  
F. Schulze ◽  
R. Clos ◽  
K. Haberland ◽  
...  
Keyword(s):  
Low Cost ◽  
Group Iii Nitrides ◽  
In Situ Monitoring ◽  
Attractive Alternative ◽  
Light Emitting ◽  
Group Iii ◽  
Light Emitting Devices ◽  
Thermal Expansion Coefficients ◽  
Long Time

Due to the lack of GaN wafers, so far, group-III nitrides are mostly grown on sapphire or SiC substrates. Silicon offers an attractive alternative because of its low cost, large wafer area, and physical benefits such as the possibility of chemical etching, lower hardness, good thermal conductivity, and electrical conducting or isolating for light emitting devices or transistor structures, respectively. However, for a long time, a technological breakthrough of GaN-on-silicon has been thought to be impossible because of the cracking problem originating in the huge difference of the thermal expansion coefficients between GaN and silicon which leads to tensile strain and cracking of the layers when cooling down. However, in recent years, several approaches to prevent cracking and wafer bowing have been successfully applied. Nowadays, device-relevant thicknesses of crackfree group-III-nitrides can be grown on silicon. To reach this goal the most important issues were the identification of the physical origin of strains and its engineering by means of in situ monitoring during metalorganic vapor phase epitaxy.

scholarly journals Optical Fiber Sensing Cables for Brillouin-Based Distributed Measurements

Sensors ◽  
2019 ◽  
Vol 19 (23) ◽  
pp. 5172 ◽  
Author(s):  
Filippo Bastianini ◽  
Raffaella Di Sante ◽  
Francesco Falcetelli ◽  
Diego Marini ◽  
Gabriele Bolognini
Keyword(s):  
Optical Fiber ◽  
Thermal Stresses ◽  
Optical Loss ◽  
In Situ Monitoring ◽  
Fiber Sensing ◽  
Optical Attenuation ◽  
Long Time ◽  
Optical Fiber Sensing ◽  
Distributed Optical Fiber

Brillouin distributed optical fiber sensing (Brillouin D-FOS) is a powerful technology for real-time in situ monitoring of various physical quantities, such as strain, temperature, and pressure. Compared to local or multi-point fiber optic sensing techniques, in Brillouin-based sensing, the optical fiber is interrogated along its complete length with a resolution down to decimeters and with a frequency encoding of the measure information that is not affected by changes in the optical attenuation. The fiber sensing cable plays a significant role since it must ensure a low optical loss and optimal transfer of the measured parameters for a long time and in harsh conditions, e.g., the presence of moisture, corrosion, and relevant mechanical or thermal stresses. In this paper, research and application regarding optical fiber cables for Brillouin distributed sensing are reviewed, connected, and extended. It is shown how appropriate cable design can give a significant contribution toward the successful exploitation of the Brillouin D-FOS technique.

In-Situ Monitoring of Pitting Corrosion in Aluminum Alloy 2024

CORROSION ◽  
1998 ◽  
Vol 54 (6) ◽  
pp. 451-458 ◽  
Author(s):  
C.-M. Liao ◽  
J. M. Olive ◽  
M. Gao ◽  
R. P. Wei
Keyword(s):  
Aluminum Alloy ◽  
Pitting Corrosion ◽  
In Situ Monitoring ◽  
Aluminum Alloy 2024

scholarly journals In-Situ Formation of Stable Oxides in Molten Aluminum Alloy by Ultrasonic Stirring

1998 ◽  
Vol 62 (6) ◽  
pp. 570-576 ◽  
Author(s):  
Yoshikazu Genma ◽  
Hidekazu Suzuki ◽  
Yoshiki Tsunekawa ◽  
Masahiro Okumiya ◽  
Naotake Mohri
Keyword(s):  
Aluminum Alloy ◽  
Molten Aluminum ◽  
Molten Aluminum Alloy ◽  
In Situ Formation ◽  
Ultrasonic Stirring
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