Surface World July 2020 Handbook | Page 169

SCIMED LTD yet to agree a sunset date for banning its use as an architectural aluminium pretreatment, as a result these chrome based systems will continue to be available for use. Global HQ, QUALICOAT Zürich, is currently working to ensure that the few applicator production testing failures still reported, are reduced to 0%. The only non-controlled area of the powder coating process is the aluminium alloy itself. Extensive research into the quality of the aluminium used in architectural coatings is being undertaken in a new QUALICOAT working group. Known as ‘QUALICOAT 3.0’, it is currently looking into the impact of various levels of recycled content within aluminium extrusion on the adhesion of powder coating under the available pre-treatment methods. Ongoing training of lab technicians working within applicator members, is a prerequisite of holding a QUALICOAT licence. The next course is still planned to take place in September at pretreatment specialists Chemetall in Milton Keynes. Lab technicians, who continually check the quality of powder coating output in applicator licence holders, require updating on the latest methodology in testing and recording which is provided by the course. Copies of the sixteenth edition of the QUALICOAT Standard, is available through the UK Association website, www.qualicoatuki.org together with an up-to-date list of licensed Powder Suppliers, Pretreatment Suppliers and Applicators. Printed literature and telephone support is available from QUALICOAT UK & Ireland Head Office in Birmingham on 0330 236 2800 or email [email protected]. The Association can also be followed on Twitter @Qualicoatuki. Quality control for industry’s most common plated finish Electroless nickel (“EN”) is industry’s most common plated finish. It’s widely used for applications that demand wear resistance, hardness and corrosion protection – particularly if parts have complex geometries. It is also used in PCB manufacturing within a process known as ENIG - electroless nickel immersion gold. EN is most valued by manufacturers because it is electro-less – and thus does not need electricity to run – and because deposits are highly uniform: EN plates evenly regardless of substrate shape. This is an important advantage over electroplating, which is subject to flux-density issues due to the electromagnetic field which shifts with surface profile. It also has a wide deposition window: from 10 microinches to about 4 mils. Electroless nickel is either nickel phos or nickel boron alloy. In either case, the percent of phosphorus in the reducing agent is a metric whose importance can’t be overstated. EN is, in fact, classified by its phos content: low at 1-4%, mid at 5-9% and high at 10-14%. Quantifying phosphorus is critical to EN plating primarily because of its direct effect on corrosion performance, and on hardness. The exceptional hardness of low-phos EN (typically 500-720 HK) has made electroless nickel a popular replacement for chromium. (To put this in context, the hardness range of electrodeposited nickel is 150-400 HK.) Many platers don’t test for phos content in-house, however, relying instead on their chemical suppliers - or an outside lab. CONTINUED ON PAGE 168 twitter: @surfaceworldmag 2020 - 2021 167