Evaluation of Electrical Contact Material Stability on Mercuric Iodide

1993 ◽  
Vol 302 ◽  
Author(s):  
A. Y. Cheng
Keyword(s):  
Free Energy ◽  
Room Temperature ◽  
Electrical Contact ◽  
Radiation Detection ◽  
Electrical Contacts ◽  
Contact Material ◽  
Mercuric Iodide ◽  
Energy Data ◽  
Contact Materials ◽  
Temperature Radiation

ABSTRACTMercuric iodide detectors are leading candidates for room-temperature radiation detection applications. The inherently reactive nature of mercuric iodide limits the number of materials suitable for fabrication of electrical contacts. The theoretical stabilities of elemental contact materials on mercuric iodide were evaluated at 25°C. Additionally, the stabilities of transparent conductive compounds, for photodetector applications, were studied. Calculations were based on Gibbs free energy data, estimates and a series of hypothesized reactions with mercuric iodide. Leading candidate materials were identified and compared to experimental results.

Process Monitoring for Fabrication of Mercuric Iodide Room Temperature Radiation Detectors

1993 ◽  
Vol 324 ◽  
Author(s):  
J. M. Van Scyoc ◽  
T. E. Schlesinger ◽  
H. Yao ◽  
R. B. James ◽  
M. Natarajan ◽  
...  
Keyword(s):  
Room Temperature ◽  
Radiation Detectors ◽  
Electrical Contacts ◽  
Careful Study ◽  
Mercuric Iodide ◽  
Optical Functions ◽  
Processing Step ◽  
Material Choice ◽  
Temperature Radiation ◽  
Processing Steps

AbstractIn the fabrication of mercuric iodide room temperature radiation detectors, as in any semiconductor process, the quality of the final device can be very sensitive to the details of the processing steps. Each processing step can either reduce the intrinsic defects and those extrinsic defects introduced by earlier steps, or it can introduce new defects. In mercuric iodide these defects can act as trapping and recombination centers, thereby degrading immediate device performance or leading to long-term reliability problems. With careful study and monitoring of each step, the process can be modified to improve the end product. In this work we used several techniques to study processing steps and their effects. Photoluminescence spectroscopy and photoionization revealed defects introduced during processing. One critical step is the formation of electrical contacts, as both the material choice and deposition method have an impact. Four point probe sheet resistance methods were used to characterize the loss of material from the contact as it reacted with or moved into the bulk semiconductor. Ellipsometry was used to characterize the intrinsic optical functions of the material, and to study the effects of surface aging on these functions. Results from this work provide suggestions for the modification and monitoring of the detector fabrication process.

The Fabrication of Mercuric Iodide Detectors for Use in Wavelength Dispersive X-Ray Analysers and Backscatter Photon Measurements

1982 ◽  
Vol 16 ◽  
Author(s):  
John H. Howes ◽  
John Watling
Keyword(s):  
Room Temperature ◽  
Gamma Ray ◽  
Surface Passivation ◽  
Electrical Contact ◽  
Scintillation Counter ◽  
Radiation Detectors ◽  
Nuclear Radiation ◽  
Gamma Ray Spectrometry ◽  
Mercuric Iodide ◽  
X Ray

ABSTRACTThis paper describes the fabrication of mercuric iodide nuclear radiation detectors suitable for X and gamma ray spectrometry at room temperature. The active area of the detectors studied are between 0.2 and 1.5cm sq and they are up to 0.5mm thick. The method of producing a stable electrical contact to the crystal using sputtered germanium has been studied. The X-ray resolution of a 1.5cm sq. area detector at 32 keV is 2.3 keV FWHM when operated at room temperature in conjunction with a time variant filter amplifier. A factor which is important in the fabrication of the detector is the surface passivation necessary to achieve a useful detector life.This type of detector has been used on a wavelength dispersive X-ray spectrometer for energy measurements between 10 and 100 keV. The advantages over the scintillation counter, more commonly used, is the improved resolution of the HgI2 detector and its smaller size. The analyser is primarily used for the detection of low levels of heavy metals on particulate filters. The detectors have also been used on an experimental basis for gamma ray backscatter measurements in the medical field.

A Study on the Development of Environment-Friendly Ag-SnO2 Electric Contact Materials through a Powder Metallurgy

2007 ◽  
Vol 539-543 ◽  
pp. 2761-2766 ◽  
Author(s):  
Hoon Cho ◽  
Duck Young Hwang ◽  
Hyung Ho Jo
Keyword(s):  
Powder Metallurgy ◽  
Manufacturing Process ◽  
Electrical Contact ◽  
Image Analyzer ◽  
Contact Material ◽  
Electric Contact ◽  
Contact Materials ◽  
Grain Distribution ◽  
Sno2 Powder ◽  
Electric Contact Material

It is generally known that Ag-CdO electric contact material excels others in characteristics. Thus, the contact material has been widely used, regardless of current strength. However, in a view point of environment, the advanced electric contact material without environmental load element such as cadmium has to be developed. Extensive studies have been carried out on Ag-SnO2 electric contact material as a substitute of Ag-CdO contact materials. In the manufacturing process of Ag-SnO2 electric contact material, it can be mentioned that typical internal oxidation process is not suitable to produce Ag-SnO2 electric contact material because the Sn located around surface may interrupt oxidation of Sn in the middle of material. Therefore, in the present study, powder metallurgy including compaction and sintering is introduced to solve the incomplete oxidation problems in manufacturing process of Ag-SnO2 electrical contact material. The formation of the blends was manufactured by wet blending of powders of Ag and SnO2. The quantity of SnO2 powder was 15wt.%, with intent to optimize the powdering process for the minute powder of which diameter is less than 5μ m. Particle size and grain distribution of Ag powder and SnO2 powder by powder metallurgy were measured by image analyzer. In order to estimate the properties of specimen tested with a variation of mixed time, the micro-hardness measurement was carried out. The Ag-SnO2-based contact material, which was produced through this study, was actually set in an electric switchgear of which working voltage is 462V and current is between 25 and 40A, for the purpose of testing its performance. As the result, it excelled the existing Ag-CdO-based contact materials in terminal-temperature ascent and main contact resistance.

Investigation of Cadmium Manganese Telluride Crystals for Room-Temperature Radiation Detection

2010 ◽  
Vol 39 (7) ◽  
pp. 1053-1057 ◽  
Author(s):  
G. Yang ◽  
A. E. Bolotnikov ◽  
L. Li ◽  
G. S. Camarda ◽  
Y. Cui ◽  
...  
Keyword(s):  
Room Temperature ◽  
Radiation Detection ◽  
Cadmium Manganese Telluride ◽  
Manganese Telluride ◽  
Temperature Radiation

Investigation on Microstructure Transformation and Failure Behavior of Cu-Cd-Nb-CP Electrical Contact Material

2005 ◽  
Vol 475-479 ◽  
pp. 869-872
Author(s):  
Yu Sheng Cui ◽  
Wen Zhu Shao ◽  
L. Zhen ◽  
V.V. Ivanov
Keyword(s):  
Grain Size ◽  
Grain Boundaries ◽  
Electrical Contact ◽  
Optical Microscope ◽  
Metallic Phase ◽  
Electrical Contacts ◽  
Failure Behavior ◽  
Contact Material ◽  
Electrical Contact Material ◽  
Micro Cracks

Dependence of microstructure upon transfer stability of the powder-metallurgy copperdiamond electrical contact material with Cr and Nb addition during type-test process is investigated by optical microscope and SEM observation. During making and breaking process, micro-cracks occurred along grain boundaries under electrical and mechanical forces. Addition of cadmium into the composite increases oxidizable capability of this material, and also leads to oxide accumulation along grain boundaries. These factors reduce the reliability of electrical contacts in practice. Arc erosion quantities during commutation operation processes relates with grain size of matrix and particle size of the second metallic phase. The optimal grain size is 20~50µm and 10~20 µm for niobium particles in these tests.

Preparation and Study on Nano-Ag/SnO2 Electrical Contact Material Doped Rare Earth Element

2014 ◽  
Vol 789 ◽  
pp. 270-274 ◽  
Author(s):  
Yan Cai Zhu ◽  
Jing Qin Wang ◽  
Hai Tao Wang ◽  
Li Qiang An
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Earth Element ◽  
Electrical Contact ◽  
Sol Gel ◽  
Fusion Welding ◽  
Electrical Performance ◽  
Contact Material ◽  
Contact Materials ◽  
Electrical Contact Material

As a new type of electrical contact material, Ag/SnO2 has poor processing performance and large contact resistance, which limits its application so far. In order to improve the machinability and electrical performance of the Ag/SnO2 electrical contact materials, a new kind of nanoAg/SnO2 electrical contact material doped rare earth element Ce was prepared by sol-gel-chemical plating method. The purity of the powders was analyzed by X-ray diffraction (XRD) and the crystallite size of the nanoparticle was calculated according to the Scherrer equation. The distribution of Ce-doped SnO2 powers were studied using scanning electron microscopy (SEM). In parallel, rated making and breaking experiments on nanoAg/SnO2 were conducted. The results of XRD and SEM show that the nanoSnO2 powders are small, uniform and with no obvious phenomenon of reunion, and thus significantly improve the density, strength and machinability of the sample. Furthermore, the results of arc erosion show that the nanoAg/SnO2 electricity contact materials doped element Ce have superior fusion welding resistance properties.

scholarly journals Comparative Study of the Properties of Cu-Cr-Mo System Electrical Contact Material by Sintering and Infiltration Methods

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 700
Author(s):  
Yeong-Woo Cho ◽  
Jae-Jin Sim ◽  
Jong-Soo Byeon ◽  
Taek-Soo Kim ◽  
Kee-Ahn Lee ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Relative Density ◽  
High Voltage ◽  
Raw Materials ◽  
Electrical Contact ◽  
Green Compact ◽  
Contact Material ◽  
Mixed Powder ◽  
Contact Materials ◽  
Infiltration Method

Contact materials in high-voltage vacuum interrupters require properties such as high conductivity, density and hardness to minimize arc heat damage. In this study, Cu–Cr–Mo alloy contact materials were examined for their usage as high-voltage contact materials. Ball milling was performed after analyzing the raw materials of the Cu, Cr and Mo powders. A green compact was produced using high pressure with a mixed powder. Subsequently, the composite was produced by sintering via the temperature and infiltration method according to the Cu content in the green compact. The composite sintering method produced a density of 8.55 g/cm3 (relative density 93%), a hardness of 217 HV and an electrical conductivity of 40.7% IACS at 1200 °C. The composite of 10 wt.% Cu produced by the Cu infiltration method exhibited a density of 8.7 g/cm3 (relative density 94%), hardness of 274 HV and electrical conductivity of 39 IACS% at 1300 °C. The measurements of the physical properties of our newly established method demonstrated a new possibility of using the Cu–Cr–Mo alloy as a contact material for high-voltage vacuum interrupters.

scholarly journals State of the art and challenges in development of electrical contact materials in the light of the RoHS directive

2012 ◽  
Vol 44 (2) ◽  
pp. 245-253 ◽  
Author(s):  
V. Cosovic ◽  
A. Cosovic ◽  
N. Talijan ◽  
D. Zivkovic ◽  
Z. Zivkovic
Keyword(s):  
State Of The Art ◽  
Electrical Contact ◽  
Electrical Contacts ◽  
Hazardous Substances ◽  
Original Form ◽  
Contact Materials ◽  
Eu Directive ◽  
Rohs Directive ◽  
Electrical Contact Materials ◽  
The Eu

The article surveys current state of the art and challenges in the development of the electrical contact materials in the light of the EU Directive on Restriction of Hazardous Substances (RoHS). The focus was placed on widely used silver-cadmium alloys. According to this directive, as of July 1, 2006, use of six hazardous materials, including cadmium, are restricted for applicable electrical and electronic products intended for the EU market. In contrast, traditionally preferred material for production of electrical contacts is Ag-CdO, due to its outstanding functional properties. These conflicting interests result in present state where RoHS directive has not yet been implemented in its original form and has undergone numerous amendments and exceptions regarding the use of cadmium. Main reason for this seems to be the unrealistic time frame imposed by legislation. Although, significant effort has been put into research and development of alternative materials, there are still cases where adequate replacement materials had not been found. Therefore, importance of synchronicity between legislation and technological progress i.e. communication between legislative administration and industry and academia is brought to light as well as some common issues that may arise with an introduction of new replacement materials or product modification.

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