Copper Chromium (CuCr) Contact Materials for Vacuum ... - Plansee

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$Refractory metals in furnace construction and engineering$

* Typical data for calculations in contact design but not valid for specifications ••••• excellent, •••• good, ••• satisfactory, •• sufficient * Typical data for calculations in contact design but not valid for specifications Impurities* CC 75 CC 75 HMA CC 57 CC 57 HMA O [ppm] 650 650 700 700 H [ppm] 5 5 10 10 N [ppm] 100 100 110 110 Physical properties* CC 75 CC 75 HMA CC 57 CC 57 HMA Density [g/cm³] 8.05 8.15 7.60 7.65 Hardness [HV30] 70 85 85 90 Electrical conductivity [m/Ωmm 2 ] 31 32 21 22 Welding tendency •• ••• •••• ••••• Operating principle For practical applications the Cr content varies between 25 and 60 wt.-%. For applications where arc quenching at low and high frequencies and low current chopping values are significant, CuCr contact materials with 25 wt.-% Cr provide the best results. For applications where erosion resistance and welding behaviour is im- portant, CuCr contact materials with 40 to 60 wt.-% Cr are used. Besides the optimum Cr content, the contact geometry also has a significant influence on the performance of the contacts, for the different switching applications.
Microstructure of PLANSEE CuCr Materials for Vaccum Interrupters Microstructure of CuCr contact material with 25 wt.-% Cr Microstructure of CuCr contact material with 43 wt.-% Cr A benefit of the CuCr contact material is the high oxygen affinity of the Cr, which acts as a getter for any oxygen released by the switching process. Special production processes based on powder metallurgical techniques are employed for production of high purity contact materials. CuCr contact materials are produced by a powder metallurgical process which includes mixing of the Cu and Cr powders, pressing and sintering below the melting point of copper. The microstructure of the contact material is influenced by the grain size of the Cr powder used. The use of fine grained Cr powders has beneficial effects on the chopping behaviour and breakdown voltage of the contact. CuCr contact materials produced by sintering may exhibit a small amount of retained porosity which leads to an improvment of the LBD behaviour at higher Voltage ranges. In some applications this can influence the breaking capacity of a circuit breaker. By subse- quent reduction of porosity after sintering i.e. by repressing, the electrical and thermal conductivity can be increased. The reduced porosity also leads to an improvement in breaking capacity. All contact materials from PLANSEE Powertech AG are produced in accordance with ISO 9001 and are designed to meet detai- led customer specifications. We are pleased to support you in selecting the optimum contact material.
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Copper Chromium (CuCr) Contact Materials for Vacuum ... - Plansee

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