Welding fume reduction by nano-alumina coating on electrodes – towards green welding process

Abstract

Fume reduction from the welding process is important from the perspective of environmental pollution and protection to the health of the welder. A novel method of reducing welding fumes at source towards green welding process has been worked out after nano coating of conventional electrodes. This method involves the dipping of a core welding wire, prior to its flux coating, in a sol containing aluminium iso-propoxide, to obtain a thin film of nano alumina coating. The nano-coated electrodes did reduce the concentration of fumes up to 62% in the welder's breathing zone, when tested vis-à-vis the concentration from uncoated counterpart. A substantial reduction in the concentration of metallic constituents in the fumes of coated electrodes was noted too. Central Composite Design matrix of response surface methodology was applied in designing these experiments and investigating the effect of coating process parameters on the welding fumes at the breathing zone of the welder. The reduction was found to be more for a homogenous deposit with lower crystallite size. Metallographic studies of the weld from nano-alumina coated electrodes showed fine grained acicular and widmanstatten ferrites with increased hardness. This is one of the first studies that verified experimentally the role of parameters such as crystallite size, specific heat capacity and latent heat of fusion through nano coating of electrode wire, in reducing the concentration of airborne particulates in welding fumes.