HARD CHROME REPLACEMENT

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1 bv Impact 4, 6921 RZ Duiven P.O. Box 1027, 6920 BA Duiven The Netherlands Tel: Fax: Homepage: Inc Charlevoix Dr. SE Suite 203 I Grand Rapids, MI USA Tel: Fax: Twilmert@aol.com Homepage: HARD CHROME REPLACEMENT For many years, Hard Chrome plating has been a well excepted coating technology, providing good wear resistance as well as good corrosion resistance and fine surface finishes. Because the plating solutions contain hexavalant chromium ions, which are carcinogenic, many environmental and financial sanctions, have been imposed during the last few years. The cost for hard chrome plating has been on a consistent upwards trend, and is projected to continue to escalate. FST Distribution/Agent COPIES IN PDF FORMAT ARE AVAILABLE, PLEASE CONTACT FLAME SPRAY TECHNOLOGIES TO RECEIVE A COPY. Alternative coatings have been developed over time and out-perform the hard chrome plating. Both carbide, metallic and ceramic coatings applied by a HVOF or Plasma process have proven to be successful. The availability of a large number of different materials has created the opportunity to tailor the coating for a specific application; resulting in excellent performances. 1

2 as part temperature, influence the wear resistance properties. It can be concluded that most coating materials out-perform hard chrome plating. These materials include: FST M-771, FST K-624, FST K- 647, FST K-854, C-335, C-604. Coating Loss meassured by ASTM G65 Rubber Wheel Test Many Ball Valves are now being coated by means of thermal spraying Coating Loss m 3 /Nm x Typical materials include: FST M-654 Stainless Steel FST M-771 Self Fluxing Alloy FST M-341 Alloy C FST K-624. WC-Co FST K-647 WC-Co-Cr FST K-854 CrC-NiCr FST C-604 Cr2O3 FST C-335 Al2O3-TiO2 (Other materials are available) WEAR RESISTANCE Chrome plating is often used to resist abrasive wear, which typically occurs when a hard surface or particles rub on a part. Although many factors, such as the erodent composition, size, shape, rate, velocity and angle of impingement, as well K-647 WC-Co-Cr Chrome Plating CORROSION RESISTANCE Hard Chrome plating is often used to protect parts against atmospheric and sometimes chemical corrosion. Generally, it can be stated that the corrosion resistance is improved when coatings are dense (HVOF & Plasma) and sealed. Further, the corrosion resistance strongly depends on the chemical composition of the selected coating material. Ni-based alloys, and materials with a high chromium content typically show good atmospheric and chemical corrosion resistance. For severe chemical environments Alloy C and Alloy 625 can be thermal spayed. 2

3 Plasma sprayed ceramics provide good oxidation protection and are resistant to most acids and alkalies. Thermal spray equipment is smaller, less expensive and portable There is no part size limitation for thermal spraying. If a part cannot be moved into a shop, the thermal spray equipment can be used in the field. Hydraulic piston rod coated with a ceramic coating TEMPERATURE CAPABILITY Hard chrome typically has a max. service temperature of approx. 480 C (800 F). Almost all thermal spray materials have higher service temperature capabilities and will vary from 580 C to 850 C (1000 F to 1500 F). Advantages of Thermal Spraying over hard chrome plating: Elimination of the toxic issues related to hard chrome plating. Smaller disposal problem. Bond strength is usually better. A wide range of materials available to choose from. Coatings can be engineered to fit an application. Many thermal spray materials have no thickness limitations and high deposit rates making thick coatings economically feasible. Thermal spraying does not affect the base metal (such as hydrogen embrittlement) and normally does not require subsequent heat treatment(s). The Thermal spray process is much simpler. It only requires three steps, while Plating requires at least 8 steps. 3

4 INDUSTRIES Thermal spray coatings as alternatives to Hard Chrome plating can be found in many industries including: Pump Manufacturing and Repair Textile Machinery Printing Industry and repair Petrochemical Automotive Plating Shops Off-Shore Earthmoving Equipment Hydraulics And many more THERMAL SPRAY PROCESSES has the capability to offer a complete product, from coating and application development, to the supply, delivery and installation of the thermal spray equipment. Our product range includes: MP-100-APS/HVOF Systems M-APS/II Plasma Systems HV-Air Fuel System HV-Wire/Powder System Accomplished with a wide range of thermal spray materials is your partner in thermal spraying. COMPARISON OF THERMAL SPRAYING WITH HARD CHROME PLATING Hard Chrome plating is a process that transfers metal ions from a liquid solution to a metallic surface under the influence of an electric current. The most common method is deposition from aqueous solutions, many which are toxic. During the plating process, water decomposes and hydrogen is deposited at the surface being plated. This might cause hydrogen embrittlement of various steels unless they are heat treated immediately after the plating process. Plating is usually limited to the deposition of relatively thin, dense layers of pure metals or simple alloys. A limited range of compositions may be plated. Electrically conductive substrates are essential, limiting the number of materials that can be plated without a pre-treatment. 4

5 Thermal sprayed coatings are used extensively for a wide range of industrial applications. The technique generally involves the spraying of molten powder or wire feedstock, the melting being achieved by oxy-fuel combustion or an electrical arc (arc spraying or plasma). The molten particles are accelerated by the hot gas stream, followed by impacting onto a properly prepared substrate. Rapid solidification produces an ultrafine grained as-sprayed deposit, having the properties associated with such microstructures. The materials which are sprayed include most metallic and carbide based alloys and ceramics. In fact, virtually any material can be thermal sprayed as long as it does not decompose prior to melting. A wide range of materials can be thermal sprayed for a variety of applications, ranging from gas turbine technology to the electronics industry. Applications include protection from wear, high temperatures, chemical attack and environmental corrosion protection. The following thermal spray processes are in use today: Combustion flame spraying (with wire or powder) High Velocity Oxy-Fuel Spraying (HVOF) with extremely high flame and powder particle velocities, creating very dense coatings. Electric arc spraying, where two electrically conductive wires are fed into a common arc point at which melting occurs. The molten material is continuously atomized by compressed air. Plasma spraying, utilizing the high temperatures and velocities of ionised gas (plasma) There are numerous applications of thermal spraying which are now evolving. The application of thermal spray coatings to replace Hard Chrome plating is one example that proves the versatility, high quality and reliability of this proven technology. The various thermal spray processes are distinguished on the basis of the feedstock characteristics (wire/powder) and the heat source employed for melting. 5