Some applications of high velocity oxygen fuel (HVOF) flame sprayed WC cermet coatings in paper mills are summarized. The WC cermet sprayed coating is one of the most widely used in the thermal spray industry. HVOF sprayed WC cermet coatings have such excellent physical and chemical properties that they are extensively employed in the industrial field. Typical properties for example, are wear resistance, high stress rotating bending or rolling contact fatigue strength, frictional characteristics, wettability for aqueous agent, non picking or non adhesive property against foreign material, thermal conductivity, mirror finished surface property and so on. They are derived from the compact, denser microstructure, containing fine-sized hard WC particles, high bond strength onto substrate. These characteristics obtained by HVOF sprayed WC cermet coatings are utilized to improve the surface functions of machine parts which are installed mainly in the press department, drying department, size press, calender department and finishing department of paper mills. In this study, examples of some application of WC cermet coatings in several types of rolls in paper mills are introduced.

The demand for better paper qualities and for higher speed of the paper web requires a constant technological development of the existing calendering process. An important factor in modern calendering is the heated metal roll. Its surface has an important influence on the gloss and the smoothness of the paper. During operation these rolls are heated to temperatures of up to 200°C. Additionally, the rolls are exposed to severe abrasive wear by fine hard filler materials and to corrosion by the moisture of the paper. The SUMECAL coating systems - especially developed for calender rolls - surpass the hard chromium platings by far regarding the scratch and wear resistance and demonstrate better calendering properties. Paper text in German.

Raising demands in industry lead to the request of better and enhanced functional surfaces, also on rolls parts in paper producing machines. Due to the higher usage of post-consumer recycled fibers on paper machines the run ability and machine cleanliness become a major issue. On one hand the contaminates called stickies can be responsible for sheet brakes, holes in the paper, web picking etc. On the other hand more sand containing waste paper enhances the impact on roll surfaces in operation. In this paper the different stickies (micro / macro / primary / secondary) and their impact on the paper production will be explained and the development to avoid stickies and contaminations together with high wear resistant coatings on roll surfaces in the paper machinery will be shown. Therefore a comparison of different materials and technologies regarding surface energy and peel force measurements are explained. Together with results of a pilot scale blade test rig the results in the market regarding anti stick properties wear resistance and corrosion resistance of the developed layer stack designs will be introduced.

In the sieve section of a paper producing machine, where the formation of paper occurs, a polyethylene sieve is guided over a set of ceramic blades to remove the water in the paper slurry. These sieves are running with velocities of 70 km/h and more. The high velocities lead to defects in the tissue structure of the sieve as well as on the blades. Moreover the presence of high abrasive particles like kaolin and carbonates in the paper slurry as well as its corrosive characteristics enforce the material wear. Present solutions include bulk ceramic blades but they cause defects on the sieves and they are quite expensive. New solutions are desired where these bulk ceramic blades can be replaced by intelligent coating systems that on one hand exhibit an extraordinarily high wear resistance but can minimize the wear of the PE sieve on the other hand. The presentation gives first results obtained by different types of ceramic and cermetic coating systems manufactured by thermal spray technology.

Raising demands in industry lead to the request of different and better paper quality. New paper types like e.g., liquid food packaging (lfp) will replace former solutions like Tetrapak, magazine papers will be produced much cheaper on different machine designs. Since certain paper properties like roughness, printability, … still remain or step up in quality level. One machine component influencing the paper properties strongly is the calender with its extremely hard, coated roll surfaces. The hard metal coating on the calender rolls can determine the later paper quality significantly. The current work describes investigations on certain WC based HVOF coatings, which later will be in contact with the paper under high temperatures, extremely high load, and steam environment. Coating design from carbide particle size, metal matrix and other factors like apparent density and sintering grade were studied under real life influences. The various coating versions were compared in a slurry test using the same fines as added in the paper production process for increasing brightness and tear strength. Interesting results are discussed on technical, but also economical basis.

This paper discusses the role of thermal spraying in the development of carbon-fiber rollers for web processing equipment. It provides a detailed review of the roller design covering key sizing and selection criteria with emphasis on roller surface performance. It describes the manufacturing process, which includes the application of a 30-35 mm HVOF-sprayed WC layer, and the tests used to verify that the coating meets design requirements and that the roller will provide stable rotation at ultrahigh speeds, sufficient traction force, and high abrasion resistance. A version of the HVOF-coated carbon-fiber roller discussed in this paper is installed in a slitter-winder, running smoothly at speeds up to 4800 rpm with no abrasive wear.

This paper discusses the different types of rolls used in paper machines, the functions and performance required of them, and recent improvements achieved with the aid of thermal spray coatings. It presents examples showing how metal and ceramic coatings applied by HVOF and plasma spraying have reduced operating expenses and extended roll life by stabilizing and improving various surface properties.

Thermally sprayed hard coatings, including tungsten carbide and chromium carbide cermets and other hard metallic materials, were studied in two types of wear tests. Surfaces of the coatings were worn by coarse and hard quartz sand in a rubber-wheel dry abrasion wear test, and by fine and soft kaolin abrasive in a wet slurry abrasion wear test. The aim of the work was to study how the surfaces retain their high polished finish and gloss, and the type of wearing of different coatings and materials. The results showed that coatings with hard tungsten carbides were worn preferentially by removal of the the binder material. Cermet coatings with softer chromium carbides, and with another types of uniform microstructures showed more uniform wear and better retained their glossy finish.

The paper deals with wear properties of various advanced oxide ceramic coatings deposited by plasma and HVOF spray processes. Several types of ceramic oxide coatings on the base of Al 2 O 3 , Cr 2 O 3 and TiO 2 are studied in the work. The coatings are characterised by their wear properties in slurry abrasion wear test with fine abrasives (kaolin) and in dry abrasion conditions with coarse abrasives (quartz sand). The surfaces of the wear tested coatings were studied by SEM. The results show that coatings with high homogeneity and minor porosity, especially HVOF sprayed and some plasma sprayed coatings perform extremely well in both of the wear tests used in the study. In the test with hard abrasive and high load, the coatings with lower interlamellar strengths seem to be more prone to wear than coatings with higher homogeneity, e.g. HVOF sprayed oxide ceramic coatings. The results can be explained on basis of type of the coating material and the coating microstructure.

The effects of globalization, technology improvement, capacity consolidation, and rising customer demands drive the printing and papermaking business worldwide. Consumption of paper, paperboard, and tissue exceeded 500 million tons in 2007, and it is estimated that one-third to one-half of this production is printed. Paper production in total is not experiencing drastic growth rates due to the increasing market share of digital media; however, market segments such as paperboard and packaging are showing growing demand. In printing, new technologies focus on production speed and quality improvement. For both printing and papermaking, the cost of energy and raw materials requires ongoing improvements in production efficiency. For equipment and machinery manufacturers serving these industries, high-end technology that lowers cost and improves quality drives the market leaders. In both industries, functional roll surfaces generated by thermal spraying help to achieve design and development objectives. The paper gives examples for the role of thermal spray coatings in both industrial areas.

A summary of the efforts involved in organizing the 1998 thermal spray conference and proceedings. Also includes a publishing history for proceedings from previous events.

Preface for the International Thermal Spray Conference 2006. Includes a publishing history for proceedings from previous thermal spray conference events.

Preface for the International Thermal Spray Conference 2001. Includes a publishing history for proceedings from previous thermal spray conference events.

Preface for the United Thermal Spray Conference 1997. Includes a publishing history for proceedings from previous thermal spray conference events.

Preface for the International Thermal Spray Conference 2000. Includes a publishing history for proceedings from previous thermal spray conference events.

Preface for the National Thermal Spray Conference 1996. Includes a publishing history for proceedings from previous thermal spray conference events.

This paper provides an overview of thermal spray activities in Finland, Sweden, Norway, and Denmark. In Finland, thermal spray technology has widest use in pulp and paper processing, protecting various types of rolls and cylinders. In Sweden, the technology is of great importance in the manufacture of aero engines and industrial gas turbines. In Norway, thermal spraying is widely used in offshore applications, including subsea oil drilling enterprises, and in Denmark, thermal spraying is used in boilers, maritime diesel engines, and for wear resistance of machine tool components. Development and innovation in thermal spray technology in northern Europe is dominated by research conducted in Finland and Sweden, followed by Denmark and Norway.

Thermal spray coatings from several different coating families have been metallographically prepared using traditional and modern metallographic techniques. The different recipes used were intended to demonstrate the effect of abrasive on coating appearance. Traditional metallographic recipes, which rely heavily on the use of silicon carbide (SiC) abrasive papers, were found to produce a notably different appearance than those prepared using modern recipes. Modern recipes, which incorporate extended diamond grinding and polishing steps, were found to produce what appears to be a more representative coating structure. Other variables, including mounting media and use of vacuum impregnation, were also found to influence coating appearance.

This paper reports on the development of a cold spray system to be used as freeform fabrication production route. Cold Spray is seen as a preferential method for additive manufacture as the cold nature of the bonding removes detrimental thermally induced stresses. The Cold Gas Dynamic Manufacturing facility is the first of its kind, housed in a CNC machining centre with integrated high-speed machining spindle for back machining of deposit material to tolerance. The process enables the production of complex geometries including undercuts through the use of a two material delivery system fed by separate powder feeders. By this method one material is used as a sacrificial support structure and removed through post-process techniques. The process is fully numerically controlled. The process is conducted inside a chamber, such that all process gas is recaptured for purification and recycling. The paper will report on the various aspects of component production and will also detail strategies and techniques for building complex component shapes. Abstract only; no full-text paper available.

In this paper, the quality control in plasma spraying of chromium oxide ceramic coating on large area substrate is studied. This paper consists of three parts. Firstly, basic technical parameters are studied, for example, electric current, voltage, gas, powder, and spray distance. Secondly, the effect of dust from the spraying process on the coating quality is studied. Finally, the character of chromium oxide coating is researched. The results show that the dust from the spraying process greatly affects the coating quality. The effect of the following variables is examined: spray parameters, the powder size and distribution, and the substrate size. We have designed a set equipment to control the coating quality and the result was excellent. Now the equipment has been used in the production of anilox rollers and the patent has been applied. Meanwhile, we have devised a standard to determine the quality when spraying ceramic coating on large area substrate. The method has proved useful and efficient. Abstract only; no full-text paper available.