A process for plating a tin-lead alloy on a substrate by displacement plating from an immersion plating solution containing dissolved tin and lead. The process includes the steps of pretreatment of a substrate by contact with a solution containing a pH adjustor for said immersion deposition solution followed by contact of the substrate with said immersion plating solution for a time sufficient to deposit an alloy of tin and lead.

A method of forming a colloidal wetting sensitizer is disclosed. The method comprises combining a stannous species and a cupric species in an aqueous medium maintained at a pH of between 0.4 and 1.5.

A coupling for preventing the buildup of static electricity between adjacent conduits includes first and second threadably engageable coupling members in electrical contact with the adjacent conduits. The threads are coated with a hard metallic ductile conductive coating which is preferably a boron-nickel coating, to provide electrical conductivity between the coupling members. The coating has a relatively low co-efficient of friction so as to prevent binding of the threads during threading. In one embodiment, a detent spring, which includes one or more resilient detents, is rotatable with one coupling member and engages with a notch or notches on the other coupling member to provide a frictional force against relative rotation between the coupling members as the coupling members threadably engage. The coupling members may be entirely coated with the boron-nickel coating, or selectively coated to provide the required electrical conductivity between the coupling members. A bonding wire in electrical contact with each coupling member makes redundant electrical contact with the conduits.

A coupling for preventing the buildup of static electricity between adjacent conduits includes a sleeve enclosed by pivotally connected semicircular segments. The semicircular segments are in electrical contact with first and second conduits via bonding wires. The semicircular segments, bonding wires, and/or flanges are coated with a hard metallic ductile conductive coating, which is preferably a boron-nickel coating, to provide electrical conductivity between the conduits. The coupling may be entirely coated with the boron-nickel coating, or selectively coated to provide the required electrical conductivity between the conduits. The conduits include flanges mounted on the ends thereof. Each flange is selectively coated with a hard anodized, dry-lube, thin-film non-conductive, or other insulating coating to reduce or prevent arcing on the interior of the coupling under lighting strike or other hazardous electrical conditions.