Silicon nitride sealing rings with diamond coating


The present invention refers to a dynamic mechanical sealing system comprising rings manufactured by means of coating silicon nitride ceramic pieces (Si3N4) with diamond films obtained by Chemical Vapour Deposition (CVD). The said mechanical elements should simultaneously warrant low friction, wear-resistance and good sealant properties. Selecting the Si3N4/diamond system herein disclosed was the result of proven thermal and chemical compatibility between both materials, thus assuring high adhesion degrees. On the other hand, Si3N4 is a light material and one of the most highly-resistant ceramics, favouring implementations involving components subjected to rotating motion. Diamond presents high hardness, excellent wear-resistance, high chemical stability, high thermal conductivity and low friction coefficient. The sealant rings obtained according to the invention can be used in fluid circulation systems.

Innovative aspects & main advantages

The invention discloses a novel dynamic mechanical sealing system comprising ceramic silicon nitride rings (Si3N4) coated with a diamond film obtained by Chemical Vapour Deposition techniques (CVD).  The sealant rings obtained according to the invention can be used in fluid circulation systems ensuring low friction, very low wear, chemical stability, low mass and good sealant properties.


Mechanical seals used in several fluid circulation systems such as fluid carrier pumps, autoclaves, steam turbines, cooling systems, spinners, mechanical stirrers, submarine and ship segmented motors, vehicle air conditioning compressors, aeronautic turbines, among other equipment. Industrial fluids contacting the sealant rings include products from chemical and pharmaceutical industries, natural gas, oil, seawater, steam, etc.


Silva, Rui; Fernandes, António; Amaral, Margarida ; Almeida, Flávia; Oliveira, Filipe ; Costa, Florinda; Carrapichano, João

Our Inventors


Universidade de Aveiro
Instituto Superior de Engenharia de Coimbra
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