SIR, With reference to Mr. G. W. Walkiden's letter, we agree in general with his remarks. Provided the titanium surface is almost completely covered with platinum, failure is most…
Abstract
SIR, With reference to Mr. G. W. Walkiden's letter, we agree in general with his remarks. Provided the titanium surface is almost completely covered with platinum, failure is most unlikely; this remark confirms Dr. Shreir's observations in the January issue of Platinum Metals Review.
Last month the author discussed platinum anodes using inert supports such as plastic and ceramic, common metal supports such as copper, and supports with passivating metal such as…
Abstract
Last month the author discussed platinum anodes using inert supports such as plastic and ceramic, common metal supports such as copper, and supports with passivating metal such as titanium or platinum. This concluding section discusses applications and operation. It is concluded that only two types of supported platinum electrode can be recommended at present—a platinum‐palladium foil anode with a plastic mount and platinised titanium.
The increasing use of platinum — containing anodes in cathodic protection and the discussions which took place at the recent International Congress on Metallic Corrosion in…
Abstract
The increasing use of platinum — containing anodes in cathodic protection and the discussions which took place at the recent International Congress on Metallic Corrosion in London, make this subject of topical interest. In this review paper the author provides a balanced overall picture of the various applications in this field. The development, advantages and limitations are described of three types of support for a thin layer of the metal, as well as an alternative use of platinum in the platinum‐lead bi‐electrode. At present only two types of platinum electrode can be widely recommended.
Non‐oxidising preservative. It is generally realised that oxidisation in a paint film is the first stage of decay. A product known as Camrex non‐oxidising preservative has been…
Abstract
Non‐oxidising preservative. It is generally realised that oxidisation in a paint film is the first stage of decay. A product known as Camrex non‐oxidising preservative has been well tested over the years, and the manufacturers, Camrex Paints Ltd., claim that it never oxidises. Only one coat is required, resulting in a saving of labour, time and material, and reducing maintenance costs. The film remains flexible, contracting and expanding with the steel to which it adheres. It is said to be unaffected by most acids, alkalis, chemical fumes and moisture.
The corrosion behaviour of lead and its alloys in sea‐water is of great commercial interest in view of the considerable use of submerged telecommunications cables and the growing…
Abstract
The corrosion behaviour of lead and its alloys in sea‐water is of great commercial interest in view of the considerable use of submerged telecommunications cables and the growing use of lead anodes for cathodic protection of marine structures. This article is concerned with the corrosion of lead in sea‐water and saline solutions and with the anodic behaviour of lead in chloride solutions.
THE APPLICATION of cathodic protection to marine structures, using both galvanic and impressed current systems, is a well‐established technique for reducing or preventing…
Abstract
THE APPLICATION of cathodic protection to marine structures, using both galvanic and impressed current systems, is a well‐established technique for reducing or preventing corrosion. It has been shown, for example, that a galvanic system applied to US Navy destroyers reduced maintenance costs by $10,000– $20,000 per ship per overhaul, and it is likely that impressed current systems will effect greater savings. Lead alloy anodes, or lead‐platinum bi‐electrodes, are being increasingly used for marine cathodic protection systems since they not only have a greater robustness than platinum or graphite anodes (and a greater coulometric efficiency than graphite) as well as lower consumption rates. The long life and ease of installation of lead alloy anodes, together with their high current carrying capacity, are strong reasons for their use.
Cathodic protection is an electrical technique for preventing the rusting of iron and steel, a phenomenon which is usually considered a chemical reaction. Because of this the…
Abstract
Cathodic protection is an electrical technique for preventing the rusting of iron and steel, a phenomenon which is usually considered a chemical reaction. Because of this the subject advances hand in hand with developments in electrical engineering and in the electrochemical industry and is modified in conjunction with advances in the chemical techniques for preventing corrosion. Magnesium, aluminium and zinc can be used as sacrificial anodes to provide cathodic protection and the greatest advance in this field has been the discovery of a new series of aluminium alloys which in sea‐water become cheap and effective sacrificial anodes. Impressed current techniques require a permanent anode and the plating of a very thin film of platinum on to a titanium substrate has been found to make an ideal anode. Much of the exploitation of this anode has taken place with new electrical techniques such as automatic control, the individual adjustment of anode current and a considerable improvement in the instrumentation. The extended experience of cathodic protection has given the contracting industry a very much greater knowledge of the design problems, of the spread of protection, of the degree of control and of the economic balance between the various techniques. A wider use of cathodic protection to supplement organic coatings and the development of coatings which work more readily with cathodic protection are two of the exceptional economic advances. Cathodic protection, unlike most anti‐corrosive treatments, is a continuous process, and as such it has to be maintained: the realisation of this has perhaps done more to produce the good results of which cathodic protection is capable, than any other single scientific discovery.
A NEW ALLOY. FEW sections of the chemical industry face bigger corrosion troubles than fertiliser manufacture. In the past a somewhat negative policy has often been followed…
Abstract
A NEW ALLOY. FEW sections of the chemical industry face bigger corrosion troubles than fertiliser manufacture. In the past a somewhat negative policy has often been followed, letting corrosion have its fling and replacing a plant or new sections of it as and when necessary. This attitude is not as easy to justify today when plant costs are so much higher, and in some factories the development of new processes with greater corrosion risks has greatly accentuated the costs of non‐prevention. The production of high‐analysis phosphatic fertilisers, which involves producing and handling phosphoric acid, is a notable example. With ordinary superphosphate manufacture the main corrosion risk comes from sulphuric acid, but in making so‐called triple superphosphate, which enjoys a high demand from farmers, phosphoric acid is used instead of sulphuric acid to dissolve the mineral rock phosphate. Other modern processes are using nitric acid instead of sulphuric acid, producing an entirely new range of ‘nitro‐phosphates.’
DEAR SIR, I have read with considerable in‐terest the articles by Mr. C. A. Curtis on ‘The Permanent Anode in Impressed‐current Cathodic Protection Systems ’ in your October and…
Abstract
DEAR SIR, I have read with considerable in‐terest the articles by Mr. C. A. Curtis on ‘The Permanent Anode in Impressed‐current Cathodic Protection Systems ’ in your October and Novem‐ber 1959 issues. I would, however, like to point out that when dealing with platinised titanium anodes his comments are misleading.
The design engineer no longer relies on the cathodic protection engineer as half‐back to provide a cure for his corrosion problems. He must ensure their prevention from the…
Abstract
The design engineer no longer relies on the cathodic protection engineer as half‐back to provide a cure for his corrosion problems. He must ensure their prevention from the outset. However, since he is now brought in at the design stage, the cathodic protection engineer must be capable of assessing the final prevailing conditions and requirements and assessing the economic advantages of protection. This brief historical summary, as well as stating the position of the cathodic protection engineer, outlines the inherent problems of the subject.