scholarly journals Mass loss of platinum-rhodium thermocouple wires at 1324°C

2021 ◽  
Author(s):  
Sivahami Uthayakumaar ◽  
Stuart Davidson ◽  
Jonathan Pearce
Keyword(s):  
High Temperature ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Mass Loss ◽  
High Temperatures ◽  
High Precision ◽  
Elapsed Time ◽  
Mass Losses ◽  
Wide Range

It is known that Pt-Rh thermocouples exhibit mass loss when in the presence of oxygen at high temperatures due to the formation of volatile oxides of Pt and Rh. The mass losses of Pt, Pt-6%Rh and Pt-30%Rh wires, commonly used for thermocouples, were considered in this paper to characterise the mass loss of wires of the three compositions due to formation and evaporation of the oxides PtO2 and RhO2 under the conditions that would be seen by thermocouples used at high temperature. For the tests, the wires were placed in thin alumina tubes to emulate the thermocouple format, and the measurements were performed in air at a temperature of 1324 °C, i.e. with oxygen partial pressure of 21.3 kPa. It was found that the mass loss of the three wires increases linearly with elapsed time, consistent with other investigations, up to an elapsed time of about 150 hours, but after that, a marked acceleration of the mass loss is observed. Remarkably, previous high precision studies have shown that a cross-over after about 150 hours at 1324 °C is also observed in the thermoelectric drift of a wide range of Pt-Rh thermocouples, and the current results are compared with those studies. The mass loss was greatest for Pt-30%Rh, followed by Pt 6%Rh, then Pt.

Characterization of YBa2Cu4O8 high temperature electrical properties and thermodynamic stability

1991 ◽  
Vol 6 (10) ◽  
pp. 2054-2058 ◽  
Author(s):  
B-S. Hong ◽  
T.O. Mason
Keyword(s):  
High Temperature ◽  
Electrical Property ◽  
Electrical Properties ◽  
Seebeck Coefficient ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Pressure Range ◽  
Stability Range

Via in situ electrical property measurements (conductivity, Seebeck coefficient) over the temperature range 500–800 °C and oxygen partial pressure range 10−4-1 atm, the equilibrium transport properties and stability range of YBa2Cu4O8 were determined. YBa2Cu4O8 behaves like the intrinsically mixed-valent compound, magnetite (Fe3O4), with small variations in electrical properties with changes in oxygen partial pressure. The decomposition boundary to YBa2Cu3O6+y (or YBa2Cu3.5O7.5±z) and CuO occurs at log(po2, atm) = −1.24 × 104/T(K) + 11.01(773 ⋚ T(K) ⋚ 1073).

High temperature potential/pH diagrams for the chlorine–water system

1985 ◽  
Vol 63 (4) ◽  
pp. 935-939 ◽  
Author(s):  
Barbara Kolodziej ◽  
Fathi Habashi
Keyword(s):  
High Temperature ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Water System ◽  
Temperature Potential ◽  
Lower Temperature ◽  
Hcl Concentration ◽  
Chlorine Water

Thermodynamic evidence supports the view that the reaction [Formula: see text] takes place above 127 °C at pH = 0. An increase in HCl concentration and/or oxygen partial pressure allow the reaction to proceed at lower temperature.

High temperature X-ray diffraction studies of the decomposition mechanism of YBa2Cu3O7−δ at an oxygen partial pressure less than 10 Pa

1995 ◽  
Vol 10 (3) ◽  
pp. 165-169 ◽  
Author(s):  
W. Pitschke ◽  
W. Bieger ◽  
G. Krabbes ◽  
U. Wiesner
Keyword(s):  
High Temperature ◽  
Solid State ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Solid State Reaction ◽  
Peritectic Reaction ◽  
Decomposition Reaction ◽  
Primary Decomposition ◽  
X Ray Diffraction ◽  
X Ray

The crystallographic data of YBa2Cu3O7−δ, Y2BaCuO5, BaCu2O2, and YBa4Cu3O9 at high temperatures and p(O2)<10 Pa have been derived on the basis of HT-XRD measurements. Whereas Y2BaCuO5 expands nearly isotropically, YBa2Cu3O7−δ and BaCu2O2 show anisotropic expansions. Furthermore, the first decomposition step of the considered compounds at p(O2)<10 Pa was observed. BaCu2O2 melts congruently at T ≍ 1273 K and Y2BaCuO5 decomposes via a peritectic reaction into Y2O3, Y2BaO4 and melts at T ≍ 1323 K. A solid-state reaction into Y2BaCuO5 and BaCu2O2 was indicated for YBa2Cu3O7−δ at T ≍ 1123 K. Because YBa4Cu3O9 becomes unstable at T ≍ 1123 K, this compound cannot be formed by the primary decomposition reaction of YBa2Cu3O7−δ

Effect of oxygen partial pressure on oxidation behavior of ferritic stainless steel AISI 441 at high temperatures

2019 ◽  
Vol 105 ◽  
pp. 215-226
Author(s):  
Maria de Fátima Salgado ◽  
Iure S. Carvalho ◽  
Rafael S. Santos ◽  
João Alberto Santos Porto ◽  
O.V. Correa ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Ferritic Stainless Steel ◽  
High Temperatures ◽  
Oxidation Behavior ◽  
Steel Aisi ◽  
Effect Of Oxygen ◽  
Stainless Steel Aisi

“Migration of Sintered Nanosilver Die-attach Material on Alumina Substrate at High Temperatures”

2010 ◽  
Vol 2010 (HITEC) ◽  
pp. 000026-000031 ◽  
Author(s):  
Yunhui Mei ◽  
Dimeji Ibitayo ◽  
Xu Chen ◽  
Susan Luo ◽  
Guo-Quan Lu
Keyword(s):  
High Temperature ◽  
Electric Field ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
External Pressure ◽  
Alumina Substrate ◽  
Electrode Pair ◽  
Electrode Gap ◽  
Die Attach ◽  
Silver Dendrites

A nanoscale silver paste that can be sintered at temperatures below 300°C without external pressure is emerging as a promising die-attach material for implementing the low-temperature joining technology in high-temperature packaging. In this paper, we report our findings on silver migration in sintered nanosilver electrode-pair patterns on alumina substrate. The electrode pairs were biased at electric field ranging from 10 to 100 V/mm and at temperature between 250 °C and 400°C in dry air. Leakage currents across the electrodes were measured as the silver patterns were tested in an oven. Silver dendrites formed across the electrode gap were observed under an optical microscope and analyzed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Silver migration was found in samples tested at 400°C, 350°C, and 300°C, and 250°C. The measurements on leakage current vs. time were characterized by an initial incubation period, called “lifetime”, followed by a sharp rise as silver dendrites were shorting the electrodes. A rapid rise in the “lifetime” with decreasing oxygen partial pressure was also found. A simple phenomenological model was derived to account for the observed dependence of “lifetime” on electric field, temperature, and oxygen partial pressure. The reliability of sintered nanosilver die-attachment over silver migration in high temperature applications can be significantly improved through packaging or encapsulation to reduce oxygen exposure.

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