Avinit duplex technologies have been developed, combining Avinit N plasma nitriding of finished high-precision parts with subsequent application of Avinit superhard antifriction coatings in a single technological process Due to the absence of a brittle layer on the nitrided surface after precision nitriding, the preservation of the original geometric dimensions that do not require further mechanical refinement, and the compatibility of the processes of plasma precision nitriding of Avinit N and the vacuum plasma deposition of functional coatings Avinit C, duplex technologies allow the deposition of strong adhered, high-quality coatings. The effect of the duplex process on the dimensions of parts during plasma nitriding of high-precision gears and the application of Avinit C functional coatings was investigated, the properties of the nitrided layer and the parameters of Avinit coatings were studied. Plasma precision technology Avinit N allows nitriding of finished parts without changing dimensions, including gears of 4 degrees of accuracy. Avinit N nitriding time is 2 ... 4 times less than with gas nitriding. The coating of Avinit C310 parts increases the microhardness of the surfaces of the parts and reduces the coefficient of friction, while it has sufficient adhesion to the working surfaces of the gear teeth and bearing raceways. Manufacturing of high-precision gears with accuracy grade 4 using Avinit duplex technologies was carried out. Analysis of the results shows that, within the measurement accuracy, no changes in the profiles of the teeth, their location on the ring gear, as well as the location of the gear ring relative to the measuring bases are observed. Plasma nitriding makes it possible to reduce the nitriding time by more than two times compared to gas nitriding, while the thickness of the layer of the brittle phase with the maximum surface hardness is ensured within the specified values ​​to ensure the necessary indicators of contact and bending long-term strength in the manufacture of gears according to the degree of accuracy 4 without grinding after nitriding. Measurements of the ring gear after nitriding and coating showed that there were no changes in the geometry of the gear processed by duplex technology. Avinit C310 anti-friction coating 1.5 microns thick does not distort the geometry of the tooth profiles. All parameters of the ring gear manufactured using the Avinit duplex technology correspond to accuracy grade 4 in accordance with the requirements of technical documentation. The gears manufactured using the Avinit duplex technology were tested as part of the AI-450M engine reducer at the Ivchenko-Progress hydraulic brake stand according to the program of equivalent cyclic tests. A pair of experimental gears were installed in the engine reducer instead of the serial wheels of the second stage of the reducer. The total test time of the wheels was 26 hours. After testing, no damage to the gear, including the Avinit coating, was found. Antifriction coating Avinit C310 with a thickness of 1.5 microns does not distort the geometry of the tooth profiles during testing as part of the AI-450M engine reducer. Measurement of the parameters of the teeth showed a complete absence of wear.