Lightweight, High Performance Material Coatings for Aerospace Applications

Introduction

Tecvac provides solutions to address the surface engineering problems found in challenging fields, including aerospace, motorsport, medical devices, and offshore oil and gas engineering.

Challenges in the Aerospace Industry

The aerospace manufacturing industry is posed by a number of technical, commercial, and environmental challenges. Manufacturers are introducing innovative solutions such as titanium in weight bearing components and lightweight materials like carbon fiber in the airframe in order to minimize fuel consumption and carbon dioxide emissions. Nevertheless, the introduction of new materials leads to new technical challenges.

Aerospace operators need to handle similar problems of lowering fuel consumption and improving revenues from the aircraft by realizing greater time on-wing and minimum time in the service bay in order to gain competitive advantage. Tecvac provides coating solutions to help achieve these goals.

Issues with Carbon Reinforced Fiber Composites

Although carbon reinforced fiber composites have benefits of weight reduction and unprecedented strength, they are difficult to drilling and cutting compared to their metal counterparts. The heat created during cutting of metal parts is dissipated through the metal by conduction, by soaking with cutting and cooling fluid, and released through the swarf created by machining.

Since carbon reinforced fiber composites are poor heat conductors, it is not recommended to drench cool. Localized heating results in smearing of the bonding resins and blunting of traditional cutting tools due to the very high hardness of carbon reinforced fiber composites requires frequent stops for changing tools.

Tecvac’s Answer to Carbon Reinforced Fiber Composite Problems

The aforementioned issues can be addressed with the application of diamond coatings. Cemecon, technical partner of Tecvac, has formulated diamond coatings capable of providing the extreme hardness required to avoid erosion by the carbon fibers. Diamond coated tools keep their cutting edge up to eight folds longer than traditionally hardened tools, with minimum heat generation to alleviate problems associated with smearing. Hence, they require fewer tool changes and eventually optimize productivity.

Titanium Problems and Tecvac’s Solution

The application of titanium as a substitute to steel and other dense metals is ever growing, thanks to its strength, corrosion resistance, and fatigue. However, the poor coefficient of friction of this material necessitates surface treatment to minimize the requirement for more frequent maintenance.

Tecvac offers a duplex coating to address this problem. In the duplex coating, stabilization of the substrate is done by the production of a hardened nitride diffusion zone in the metal surface. Then, a titanium or chromium nitride coating is applied to facilitate lubricity. Both hardening and final coating are carried out in a single PVD cycle.

Improving Aero Engine Performance

PVD applied coatings are used for several purposes within aero engines, for instance, their application in the critical compressor stage of the engine to achieve considerable and sustained fuel saving, reduced carbon emissions and prolonged service intervals. The service life of compressor aerofoils is shortened by high pressure, temperature, and the erosive forces of contaminated airflow.

These issues can be addressed with Nitron Flight, a multi-layer coating from Tecvac that is based on chromium, titanium, carbon/metal carbide or chromium/aluminum. Nitron Flight is a low-stress surface coating that is applied in 6 to 8 layers. It shows more resilience to delamination compared to a single layer coating of the same thickness.

A major European maintenance overhaul and repair contractor has achieved more than 10,000 flight hours in on- wing trials in the comparison of an untreated reference engine and an engine with a Nitron Flight treated compressor section. This showed the possibility of recovering the treatment cost within seven months and achieving savings of $156,000 per engine over a typical five year, 25,000 flight hours (FH), cycle.

Other Applications of Tecvac Coatings

Tecvac, together with technical partners Sub-One Technology, offers InnerArmor to overcome common offshore oil production issues of erosion, corrosion, wear and fouling in valves, pumps, pipework, and other hollow process vessels. InnerArmor employs PECVD to apply homogenous, pin-hole free, thin films of highly resistive titanium carbide, diamond like carbon (DLC), or other resilient coatings. InnerArmor avoids the use of high-cost exotic metals or alloys by offering an effective barrier on common metals such as mild steel.

For motorsport applications, Tecvac provides Diamolith DLC coating that integrates different carbon structures to improve the properties of diamond and graphite to obtain a naturally resistive and lubricious surface coating for automotive components. In the medical device industry, the use of prostheses in hip replacements raises concern about the entry of contaminants into the tissues of the patients caused by joint erosion due to metal on metal contact. This problem can be overcome by the use of Tecvac coatings, which ensure patient safety by producing erosion-free joints with freedom of movement.

From: http://www.azom.com/article.aspx?ArticleID=10438