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 Technical Services Support Team   WEIRTEC® Analytical has helped Weirton’s customers solve nagging problems in their processes. Using leading-edge equipment and highly trained people, problems are identified and isolated and changes are recommended. Here are a few examples of how WEIRTEC Analytical works: Case Study #1 A large tin plate user thought a surface contaminant was causing a lacquer adhesion problem on a closure. WEIRTEC Analytical personnel used the scanning electron microscope, electron spectroscopy and analyses employing plasma techniques in the laboratory investigation. The laboratory data and a week-long observation of the process in the customer’s plant verified that the problem was in the tooling. The customer made adjustments in the tooling the problem was eliminated.
A Weirton customer was concerned about the degree of corrosion resistance offered by our surface-brightened Weirzin¨. The customer preferred the Weirzin product over comparable materials, but needed additional corrosion resistance. WEIRTEC Analytical began testing products that would provide better surface protection without discoloring or dulling the bright finish. Suitable products were tested in the laboratory before going to the production line for mill trials. On the production line, modifications were necessary for applications of the passivation system. This was accomplished jointly by personnel in Mill Operations, WEIRTEC Analytical, Quality Assurance and other departments. With input from the customer, trial coils were produced. Samples from these coils were tested in the lab after which the coils were shipped to the customer to help them effectively evaluate the performance of the trial coils.
While evaluating packed TFS containers which had been coil coated with a non-metallic coating, A Weirton customer discovered what were thought to be metal fines in the sidewalls of the containers. The WEIRTEC Analytical staff immediately began an in-depth study of the problem. The defect was first observed at high magnification using the Scanning Electron Microscope. Although this didn’t disprove the metal fines theory, it did confirm the presence of a foreign substance. Energy Dispersive X-ray analysis was used to obtain the chemical composition of the substance. This analysis, combined with ESCA (Electron Spectroscopy for Chemical Analysis) revealed that the substance was primarily a piece of iron phosphate, not a metal sliver, embedded in the non-metallic coating. To determine how iron phosphate got into the coating, our staff analyzed the customer’s product which was found to be high in phosphate. Despite the presence of the non-metallic coating, this phosphate had combined with the iron to form iron phosphate. After further tests and additional analyses using EDX and ESCA, the problem was found to be caused by a porous non-metallic coating which allowed the migration of the phosphoric acid through the coating. The paint supplier reformulated the paint system to prevent the migration through the coating and the problem was eliminated.
A major consumer of hot dipped galvanized was experiencing various levels of premature
white rusting on stored, fabricated parts. After evaluating the problem at the
customer’s location, personnel at WEIRTEC Analytical used wet chemical methods,
Atomic Absorption, Inductively Coupled Plasma Emission, and electrochemical methods to
analyze the chemical baths used in the mill and the zinc-coated product. This data was
correlated with product performance in salt fog tests and humidity stack tests. The
WEIRTEC Analytical staff worked with the customer and with Mill Operations to develop a
solution to the problem. Treatment chemistries and concentrations as well as application
techniques were modified. Thanks to the cooperation between the customer, WEIRTEC
Analytical and Mill Operations, processing changes were made that significantly improved
the corrosion resistance performance of the zinc-coated products supplied to the customer
and the white rust problem was solved. |