Emerald Group Publishing Limited
Copyright © 2004, Emerald Group Publishing Limited
Corrosion test chambers
Corrosion test chambers
Keywords: Corrosion, Aircraft
Specially designed corrosion test chambers from Ascott Analytical Equipment, Tamworth, Staffordshire, UK, are set to play a minor but very important role in the international Joint Strike Fighter (JSF) project.
The JSF project, led by the US company Lockheed Martin, involves the participation of Australia, Canada, Denmark, Italy, the Netherlands, Norway, Singapore, Turkey and the UK, as well as the US, in the system development and demonstration (SDD) phase of the project.
The final aircraft – designated the “F-35” – is to built in three variants: conventional take-off and landing (CTOL), the “F35A”; short take-off and vertical landing (SVTOL), the “F35B”; and an aircraft carrier-based (CV) version, the “F35C”. All variants will have a 70-90 per cent commonality of components and systems. The aircraft is currently expected to enter service in 2008.
“The multi-billion Dollar JSF project is the biggest defence contract in history, with US and UK forces alone currently committed to procuring a total of around 3000 aircraft, in all three variants”, commented Chris Gates, Managing Director of Ascott.
All aircraft variants will have to operate under extreme weather conditions, and their component parts will be subject to rigorous testing in line with the very latest international test standards. This includes the American Test Standard “ASTM G85 annex A4”, which requires samples to be exposed to a salt spray environment, within a corrosion test chamber that also has the ability to dose the test environment periodically with sulphur dioxide gas (SO2).
The very high solubility of SO2 in water, and the mist spray method of introducing the salt solution into the chamber ensures that most of the SO2 will be dissolved into the salt spray. As a result of this, the salt spray will become strongly acidic – with a pH of between 2 and 3.
This test is therefore very aggressive and can be used to accelerate naturally occurring corrosive conditions. The test is vitally important in the case of the carrier-based F35C variant, which will operate largely in a marine environment.
Ascott's latest salt spray and cyclic corrosion test chambers are believed to be the only units of their type offering an “off-the-shelf option of an SO2 gas dosing facility for full compliance with the requirements of ASTM G85 annex A4”. This comprises a chamber-mounted dispersion tube, through which the SO2 gas can be introduced into the chamber environment, at a rate determined by the setting of a user-adjustable control valve and monitored by reference to a flow meter. The flow of gas into the chamber can be switched on and off automatically, at user programmable times, using a standard touch screen control panel.
BAE Systems, a major participant in the JSF project, has already installed three Ascott combined salt spray and SO2 corrosion test chambers at its Filton facility, near Bristol, UK, and Ascott expects other significant orders to follow soon from other companies involved in the JSF project.
Details available from: Ascott Analytical Equipment Ltd., Tel: +44 (0)1827 318040; Fax: +44 (0)1827 318049; E-mail: firstname.lastname@example.org; Web site: www.ascott-analytical.com and North American Office, Tel: +1 2486871222; Fax: +1 248 687 1001; E-mail: email@example.com, Web site: www.ascott-analytical.com