Enhancement of Heating Properties of Nichrome Cable

In the nickel-chromium alloys the chromium is easily soluble in the nickel. The solubility is highest at 47% concentration at the eutectic temperature and lowers at 30% at the normal room temperature. The group of industrial nichrome alloys is based on firm solution of nickel chromium metals. This alloy offers large resistance to oxidation conditions at the high temperature as well as it as appreciable wear resistance.   

With the inclusion of little concentration of chromium in the Nickel the alloy’s potency to oxidation is improved. The reason is that the dispersion rate of oxygen has been improved.  This process alters after the addition grades increased by 7% chromium and improves to increased level by 30%. Beyond this grade, minor changes occur. 

The oxidation resistance of nichrome heating wire to the production of extensively adherent secured level. The adherent and coherent level can further be enhanced with the inclusion of little concentrations of other materials like zirconium, silicon, cerium, calcium and more. The level produced is the combination of nickel and chrome oxides. These add up to produce nickel chromite that possesses spinal shape.

Significant improvement in the resistance of nichrome heating wire is noticed with the chromium addition such that 20% chromium is said to be the suitable material amount for resistance in the electrical equipments. Such combination provides excellent electrical features with fine potency and ductility that the material suitable for drawing.

The commercial levels consist of Nichrome and Brightray. The little upgradation for this composition can be made to improve the wire for certain operations. With the inclusion of suitable reactive alloy metals an alteration in the properties is certain. The performance conditions of nichrome alloy wire are extremely influenced by its composition.

Appropriate concentration for elements used intermittently and continuously.

Element Intermittent Continuous
Chromium 20 20
Silicon 1.5 0.5
Calcium 0.1 0.05
Cerium 0.05
Nickel Balance Balance

However the concentration alternations have minor impact on mechanical features, large concentration of reactive metals causes to avoid the flaking of scale while periodic heating and cooling.

Let’s have a brief look on the properties of Nichrome alloy wire

Feature Min. Value Max. Value Units (S.I.) Minimum Value (Imp.) Maximum Value (Imp.) Units (Imp.)
Atomic Volume (average) 0.0065 0.0072 m3/kmol 396.654 439.371 in3/kmol
Density 7.75 8.65 Mg/m3 483.817 540.002 lb/ft3
Energy Content 40 200 MJ/kg 4333.55 21667.7 kcal/lb
Bulk Modulus 110 205 GPa 15.9541 29.7327 106 psi
Compressive Strength 170 2100 MPa 24.6564 304.579 ksi
Ductility 0.005 0.7 0.005 0.7
Elastic Limit 170 2100 MPa 24.6564 304.579 ksi
Endurance Limit 130 1150 MPa 18.8549 166.793 ksi
Fracture Toughness 65 150 MPa.m1/2 59.153 136.507 ksi.in1/2
Hardness 1000 6000 MPa 145.038 870.227 ksi

The nichrome wire with binary expression of 90/10 is used for heating operations and it has highest performance temperature of 1100 degree Celsius. Moreover nichrome heating wire is also used in thermocouples.  The combination of nickel and chromium in 90:10 ratio is more preferred for thermocoupling as compare to 95: 5 nickel chromium addition.

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Isha Changotra has wide experience in metals industry and is working for a renowned super alloys manufacturer located in China and United States. With extensive insight in metals and high performance super alloys, she aims to provide most useful information for folks engaged under this niche.

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Posted in Nichrome heating wire

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