Coating on a metal substrate and a coated metal product

Abstract

The invention relates in general level to a method for coating metal products including large surface areas. The invention also relates to coated metal products manufactured by the method. The coating is carried out by employing ultra short pulsed laser deposition wherein pulsed laser beam is scanned with a rotating optical scanner including at least one mirror for reflecting the laser beam. The invention has several both industrially and qualitatively advantageous effects such as high coating production rate, excellent coating properties and overall low manufacturing costs.

Description

FIELD OF INVENTION[0001]The invention relates generally to a method for coating metal products comprising large surface areas by ultra short pulsed laser ablation. The invention also relates to products manufactured by the method. The invention has many advantageous effects such as high coating production rate, excellent coating properties and low manufacturing costs.BACKGROUNDMetal Products[0002]Ever since bronze-age, the metals and different products derived thereof have played very significant role for mankind. Even though metals possess excellent wear, chemical and physical properties, there are still many problems associated with said products. Part of those have been solved by developing the physical and chemical properties of the metal product by altering the metal material construction (alloys and composites), attempts to solve the problems associated with surface properties being not so successful.[0003]Taking the ferrous products into account, original iron has been derive...

AI Technical Summary

Benefits of technology

[0002]Ever since bronze-age, the metals and different products derived thereof have played very significant role for mankind. Even though metals possess excellent wear, chemical and physical properties, there are still many problems associated with said products. Part of those have been solved by developing the physical and chemical properties of the metal product by altering the metal material construction (alloys and composites), attempts to solve the problems associated with surface properties being not so successful.

[0003]Taking the ferrous products into account, original iron has been derived to steel, carbon steel, alloy steel, stainless steel, heat-resistant steel, tool steel and for example cast iron.

[0004]The problems with metal product surfaces deal especially with their corrosion resistance, their wear- and tribological properties, heat-resistance, but also with properties associated the use of various metal products both in construction and interior / exterior use. Typically, metal products are designed for extremely long use, and their technical, mechanical and visual properties should preferably accomplish life-times exceeding decades.

[0005]Due to continuously increasing use of metal products not only in visible construction but direct interior use, special emphasis is also put on their cleaning properties.

[0006]Metal products comprise typically large surface areas, thin sheets for example for construction and interior products being produced for example in sizes like 1200 mm×1500 mm, being then delivered to customer as plain or rolled sheets. To protect the product and increase the life-time, the problems have typically been addressed by simple coating by painting or in some cases, by electrolytic coating. For example aluminum products are typically subjected to eloxation, i.e. electrolytic oxidation by either oxalic acid or nowadays—sulfuric acid. Copper and many other metal products such as bras are oxidized due to their chemical nature, the interior effect being the desired one. Being environmentally hazardous, the leakage of copper and several other metal oxides or other derivatives is not desirable, and the problem should be solved by another protective coating simultaneously saving the interior effect of said product.

[0007]Nowadays, there is also increasing demand for products comprising the metallic look, i.e. the oxidation of the metal product surface should be prevented without loosing the original metallic decorative effect, especially on copper, bras and stainless steel. Thus, the protection

Problems solved by technology

The maintenance cost for metal products is huge and steadily increasing and there is a great need for coating technologies for especially metal products comprising large surface areas.

Neither recent high-technological coating methods, nor present coating techniques related to laser ablation either in nanosecond or cold ablation range (pico-, femto-second lasers) can provide any feasible method for industrial scale coating of metal products comprising larger surfaces.

The present CVD- and PVD-coating technologies require high-vacuum conditions making the coating process batch wise, thus non-feasible for industrial scale coating of most of the present metal products.

Moreover, the distance between the metal material to be coated and the coating material to be ablated is long, typically over 50 cm, making the coating chambers large and vacuum pumping periods time- and energy-consuming.

Such high-volume vacuumed chambers are also easily contaminated with coating materials in the coating process itself, requiring continuous and time-consuming cleaning processes.

While trying to increase the coating production rate in present laser-assisted coating methods, various defects such as pinholes, increased surface roughness, decreased or disappearing optical properties, particulates on coating surface, particulates in surface structure affecting corrosion pathways, decreased surface uniformity, decreased adhesion, unsatisfactory surface thickness and tribological properties etc. take place.

The present coating methods also drastically restrict the materials employable for coating purposes in general and thus, limit the scope of different coated metal products available on market today.

Images