WUZETEM uses advanced solutions to constantly develop its production capabilities.

The company has implemented a technology for the production of DLC coatings, which combine the high hardness typical of diamond with the low coefficient of friction typical of graphite. This type of coating, which is applied to the nozzle needles, provides greater wear resistance and less resistance to movement, which leads to a longer life of the nozzle.

The name DLC is an abbreviation of diamond-like carbon. Loosely translated, it means diamond-like carbon. In addition to its optical properties, diamond is the hardest material known to mankind. In diamond, each carbon atom is connected by strong covalent bonds to exactly four other atoms. The tetrahedral arrangement of the bonds creates a rigid, three-dimensional network, which is a guarantee of high hardness. In contrast, each graphite atom has only three covalent bonds. Atoms form planes that can easily slide between each other. Thanks to this structure, graphite is soft and provides good lubricating properties and a low coefficient of friction. In DLC coatings, there are bonds characteristic of both diamond and graphite.

“Among the various methods of DLC coating application, WUZETEM opted for the PACVD method, i.e. chemical vapor deposition with plasma support. The use of plasma lowers the process temperature and allows for uniform coatings to be applied to parts with compiled shapes. In the plasma produced at the surface of the needles, acetylene molecules decompose, and the resulting carbon atoms are deposited on the surface of the needle,” says Piotr Pawluk, Specialist in Acetylene Plastics. Metallography at WUZETEM.

Before the surface of the spray needle is coated with DLC, it is subjected to precision grinding, which ensures very low roughness. The needles are then subjected to glow nitriding to achieve a hardness gradient between the hard steel and the even harder coating. In the next step, a silicon interlayer is produced, smoothly transitioning into the actual DLC coating. This ensures the best adhesion, i.e. adhesion of the coating.

Less than the thickness of a hair

The thickness of the applied coatings is several dozen times smaller than the thickness of a human hair, and has a significant impact on the surface properties of the needle. It is thanks to the use of a DLC coating on the nozzle  needle that it is possible, among other things, to increase the resistance to frictional wear and reduce resistance to movement. In addition, corrosion resistance is greatly improved, the adhesion of impurities is reduced, which consequently leads to an extension of the service life of the atomizer.

Coatings (or process) under full control

Once the DLC coating is applied to the spray needle, the product is subjected to a detailed inspection process. The thickness of the coating is measured, the scratch test, the hardness measurement, and the impact of the simulated operating conditions are evaluated. A representative batch of needles undergoes a visual assessment to rule out the presence of possible defects.

“We use a calotech to measure the thickness of the coating at selected points on the needle. An important test is the scratch test. For this purpose, we use a precise device that makes a crack in the coating with a diamond indenter, with a uniformly increasing load. At the same time, the friction force, acoustic emission and crack profile are recorded. On this basis, in combination with the microscopic image, we evaluate the adhesion of the coating, i.e. the strength of adhesion to the substrate. Further tests include measuring the hardness of the coating and simulating operating conditions. Positive results of all tests allow the needles to be used in the further production process and guarantee the high quality of the product,” adds Piotr Pawluk.

WUZETEM is gradually developing its machine park, and the device for the production of DLC coatings and research equipment are among the company’s latest investments. The detailed technological process of applying coatings has been designed and implemented specifically for the needs of nozzle needles, which are used in the production of flagship nozzles offered by WUZETEM.

WUZETEM received the first place in the ” I like it because it’s Polish” ranking in the Innovative Product 2022 category for its Fuel Nozzles with a DLC-coated needle.