Polymer Coatings (Lectra Fluorine)
Properties that can be easily achieved using polymer or organic coatings are dielectric, chemical corrosion and radiation resistance; in addition, special organic coatings are available for food and pharmaceutical applications and comply with US Food and Drug Administration regulations.
All coatings are proprietary in that they are newly developed and have specific nomenclature (601, 604, 615, 611, etc.) for identification.
Coatings can be applied by spraying, dipping or electrostatic powder processes. In most cases, cure temperatures in the range of 300 to 750°F will achieve maximum surface hardness and minimize porosity. Polymer coatings are typically between 0.001 and 0.015 inches thick.
The salt spray resistance of these coatings is very good: about 2000 hours (6 years in the atmosphere). Chemical resistance is the main performance of 601 coating, which can withstand strong acid and alkali
At temperatures up to 2000°F. 604 material has similar resistance but can be used in food applications. 615 is a tough, durable coating (D-80 durometer) that can withstand temperatures from –400 to 500°F and can also be used in food applications. The 611 coating, which has good release characteristics, is also used in the bakery industry and is available in a variety of colours.
Magnesium (Magnadize) and Titanium (Canadize)
Since magnesium and titanium are widely used materials, especially in the aerospace and computer fields, their users often face very serious problems.
A system has been developed for hardfacing each material, which is basically an electrochemical process.
However, synergistic coating systems are still a better choice for wear applications, and special fluoropolymers or dry lubricants are injected into the overlay. For magnesium the synergistic coating is called Magnadize and for titanium it is called Canadize.
For magnesium, the thickness can vary from a minimum of 0.0002 inches to a maximum of over 0.0015 inches. Normal application thicknesses are approximately 0.0005 to 0.001 inches.
Titanium is more difficult to increase in thickness, so normal application thicknesses are between 0.0002 and 0.0005 inches.
A typical application for Magnadize is magnesium engine mounts for aircraft. The entire mount will be hard-coated, and the gear splines will get dry lube for an effective part.
A classic application of Canadizing is titanium hardware for aircraft. These assemblies are anodized with an implant thickness of 0.0002 to 0.0004 inches to prevent titanium seizing.
Titanium nitride (Magnagold)
Since the introduction of titanium nitride into the industry, coatings companies have been providing this service without a sufficient understanding of its engineering properties. The coating is considered to be very hard, and it is used exclusively in cutting tools. Investigation of this coating material, however, revealed some interesting properties, as shown in Table 35.3, Table 35.4 and Table 35.5.
One of the unique features of the titanium nitride process is the uniformity of the coating. This cannot be overemphasized for the many applications involving missiles, computers and semiconductor applications. Other excellent applications are found in the plastic extrusion industry (it takes advantage of the superior mold release properties in the mold); .
In this Magnagold process, uniform coatings, maintained at a thickness of a few millionths of an inch, are safely applied to the most critical, closer-tolerance parts through special cleaning fixtures that allow the parts to rotate 360 degrees as they pass through the steam ° Mechanics and technical streams. The process sequence is shown in Figure 35.6.
Because the part to be coated rotates the chamber radially and axially in a unique ion bombardment , there are no restrictions on the shape. In addition, all surfaces, except the jig and clamp area, were coated with a uniform thickness. Typically, thicknesses range from 0.00003 and 0.0002 inches, ultimately determined by edge sharpness and/or wear. (Load life is the final criterion for the final decision.)
Since the condition of the substrate surface is a key factor in the effectiveness of any physical steam
Deposition (PVD) process, General Magnaplate has designed a proprietary, proprietary pre-deposition surface treatment. A combination of professionally designed equipment and chemical cleaning techniques prepares component surfaces to ensure interlocking anchorage of the "coating". Conventional vapor deposition coaters are not equipped with extensive facilities that allow for the meticulous care and attention required during the pre-cleaning phase of the process. The parts are mounted in a specially designed cylindrical fixture, and then the entire working cylinder enters the vacuum chamber. vacuum (1 × 10–6 torr), then flush the system with argon as an additional cleaning step. Titanium metal (99.9%) is then vaporized by plasma energy. This is followed by the precise introduction of nitrogen (reactive gas) into the chamber. The part to be coated is passed through a high voltage (dc) with a cathodic charge, attracting accelerated titanium ions. At the same time, they are combined with nitrogen to produce a tightly adherent, highly wear-resistant titanium nitride PVD coating.
Figure 35.6 Magnagold process sequence.
