Apticote Hard Anodising for Aluminium
The Apticote 300 process is a unique approach to precision hard anodising (or hard anodizing) of Aluminium. Poeton provide a level of quality control, combined with high throughput and low turn-round times, that is unmatched by our competitors.
Poeton offer a wide range of aluminium hard anodising variations, one of which will satisfy you particular requirements for wear resistance, corrosion protection and mechanical properties. Our strength lies in the skill of our operators, with your component being processed exactly to your requirements, irrespective of the alloying content of the substrate.
Specifically, the highly innovative Apticote 300M hard anodising process gives a layer thickness on aluminium twice that which is normally achievable, producing excellent thermal and electrical insulation properties.
Excellent Wear Resistance
Tests show that, for certain aluminium alloys, the wear resistance of Apticote 300 hard anodising is similar to that of case-hardened steel (hardness 800VHN) and even that of Hard Chromium, although the micro-hardness values (reflecting the micro-cellular structure rather than actual base oxide) are only 300-500 VHN. At low loads, the wear compares favourably with that of tool steels having a hardness rating of 950 VHN. Load-carrying capability is dependent upon alloy choice. The benefit to the end-user is prolonged wear life with a substrate that provides for reduced weight and cost.
Good Corrosion Protection
Generally superior to that of chromic and sulphuric anodising (where the thin coating may be easily scratched or damaged), the corrosion resistance of Apticote 300 aluminium hard anodizing can be further improved by dichromate or acetate sealing, although there will be some loss of abrasion resistance. Typical results show >500 hours salt spray endurance on 6082 aluminium alloy. Note that alloys with a lower copper or silicon content show a lower resistance to corrosion. The benefit to the end-user is prolonged corrosion protection with a substrate that provides for reduced weight and cost.
Good Heat Resistance
Apticote 300 hard anodised coatings can withstand short exposures up to 2,000DegC, which makes them ideal for parts like rocket venturi. Long exposure to high temperatures has no adverse effect on the coating performance, other than crazing of the surface. Specifically, Apticote 300M, with a thickness over 200µ, is a very effective thermal barrier on aluminium, and it out-performs any other anodised layer in rocket venturi applications
High Dielectric Strength
Breakdown voltage increases with film thickness. Coatings normally withstand voltages in excess of 1,000volts DC. Unlike most insulators, Apticote 300 hard anodised aluminium coatings can operate at temperatures up to 2,000DegC. Its combination of high dielectric strength and thermal stability make Apticote 300 the ideal surface for mounting electrical components.
Mechanical Strength/Fatigue Strength
Losses in tensile strength due to anodising are very slight and have not prevented the widespread use of aluminium into many high-tech industries. However, anodised aluminium is not recommended for high-impact situations. Hard anodising can reduce the fatigue strength of the base material by up to 47%, depending on the alloy and the coating thickness. However, this loss can be held at 16-20 % by modifying the sealing procedure, provided a little reduction in abrasion resistance can be tolerated. Where fatigue mechanisms exist, the aluminium components benefit from ceramic shot peening before coating.
Apticote 300 aluminium hard anodising provides a uniform surface layer of predictable thickness. Component surface growth is approximately 50% of the total coating thickness, so that final dimensions can be accurately predicted. For optimum results, sharp corners should be relieved as far as possible. The benefit to the end-user is reduced machining and grinding costs and improved precision of manufacture.
Poeton are highly skilled at jigging and fixturing, so that an even coating distribution can be achieved on complex geometrical features, including down long bores, where normal anodised layers will thin.
However, it should be noted that anodising to a specific final size requires that the as-manufactured dimensions and tolerance band are both closely controlled. Tolerances are additive, so that the final size depends more on the incoming precision than on any small variations in the anodising process. Poeton strongly recommend that aluminium parts should be anodised to a specified coating thickness rather than to a defined final size.
Apticote 300 hard anodizing can be applied to a range of aluminium alloys. Best results are obtained on alloys in which the Si content is below 10% and the Cu content is below 5%.
As examples, alloy types HE30 (6082), L65 (2014), L160 (7075), DTD 735 and LM25 are particularly responsive to the Apticote 300 process.
Colour matching of hard anodised parts is near impossible, with too many variables on the parts, their method of manufacture, their heat-treatment, as well as in the details of the process, all conspiring to produce unpredictable changes in hue and shade. Poeton do not, therefore, offer colour matching with Apticote 300 on aluminium.
Technical Data Sheet
For details of all our processing capabilities, size and capacity, please follow this link.
Poeton & Apticote
supporting global manufacturing, from A to Z
Failure Analysis Projects and Coating Characterisation