OFIENGINE: improvements in maintenance and reliability of marine engines

It is expected that this technology will be capable of not only generating the coatings technically necessary to combat mechanisms of identified wear, but also of competing with the thermal projection processes in current use as regards cost, reliability and industrial accessibility.

Taking part in the project, set to last three years, is the National Centre for Scientific Research (CNRS) of the University of Limoges in France and Javikan, Arain and Mecanizados Kanter companies from the Basque Country, together with the other European companies, PyroGenesis (Greece) and BPE International Dr. Hornig GmbH (Germany).

Two-stroke diesel engines are recognised to be the most economic and reliable for ocean-going cargo ships. However, the aim of reducing maintenance requirements and enhancing reliability during operation is basic in competitiveness in the marine industry and maritime trading.

The components of this engine subjected to checks in order to increase their useful life are numerous: those of the exhaust gases exit system, the cylinder casing, the piston head, the segments and the piston rod, amongst others. The exhaust system is a substantial part of the cost of the engine given that, under the extreme conditions of corrosion and temperature, advanced high-cost materials have to be employed.

The manufacturing of exhaust valves, for example, requires materials capable of resisting both extreme conditions of erosion and adhesion of corrosive deposits, as well as the high pressures of the system. The most appropriate material for this type of valve is a Nimonic alloy, although for standard valves, steels resistant to high temperatures and with local hardening at the valve seat are still preferred.

The cost of these materials and the need to optimise the checking and maintenance intervals have given rise to developing effective maintenance and reconditioning procedures for valve components.

The usual procedures involve refilling with estelite through welding at the valve seats and the use of ceramometallic coatings applied at the valve axle using a HVOF (High Velocity Oxy-Fuel) thermal projection technique. While these techniques are included in the specifications of many of the most advanced equipment manufacturers and maintenance companies, their more general use in the manufacture of these components is limited technically and financially.

Technological objectives

The practical targets of the project focus on the following technological aims

* Reduce (in the proportion of two or three times) the maintenance requirements for critical components in marine diesel engines:
– Exhaust valves: increasing resistance to corrosion and wear of axles and seats.
– Piston crowns: increasing thermal insulation and resistance to corrosion of the piston crown.
– Piston rings: enhancing behaviour of piston rings during operation by means of the application of multiple-layer coatings.
* Reducing by 50% the cost of the process of coating components.
* Diversifying the technical solutions provided by thermal projection for marine applications by means of increasing the range of materials deposited: from low fusion-point materials, such as alloys of aluminium or copper, to super alloys, carbides and refractory ceramic oxides.
* Designing and developing of new OFI thermal projection equipment and available for marketing.

* Manufacturing diesel engine components using OFI technology.