P. Liberski

Influence of coatings obtained by PVD on the properties of aircraft compressor blades

Abstract In this paper, the results of investigations to increase aircraft compressor blade durability were presented. The blades were made of the martensitic steels. The coatings were obtained by the physical vapour deposition (PVD) method. TiN and (Ti, Al)N coatings on a titanium nitride base and CrN and CrCrN multilayer coatings on a chromium nitride base were used in the tests. Low corrosion resistance of the TiN coatings was shown in laboratory tests. The (Ti,Al)N coatings, particularly CrN and CrN modifications, behaved better. Coating density and chemical interaction of the coating and steel in the corrosive medium were shown to have an influence on the blade properties. A significant increase in the corrosion resistance was achieved by using the diffusion and chemical treatment of coatings obtained by the PVD method. Investigations of coatings in a humid atmosphere containing SO2 showed very low resistance of the steel. The resistance of the coatings was increased significantly by additional chemical treatment.

Erosion- and corrosion-resistant coatings for aircraft compressor blades

Abstract In this paper the comparative test results of protective properties of several coatings for aircraft engine compressor blades are presented. Erosion and corrosion tests for the base metals and coatings were carried out. Corrosion test for base materials and anodic coating was made in neutral salt spray. For cathodic coatings a modified corrosion test was performed. It has been determined that the coatings obtained by physical vapour deposition (PVD), particularly (Ti, Al) N and TiN(Pt) are the best in the erosion and corrosion test conditions. The electroplated Ni-Cd coatings do not show satisfactory erosion resistance, but they have good corrosion resistance. It seems that PVD coatings fulfil the requirements for the protection of aero engine compressor blades.

Synergistic influence of Al, Ni, Bi and Sn addition to a zinc bath upon growth kinetics and the structure of coatings

In this article the authors have analysed the current knowledge about the influence of alloy additions used in galvanizing baths. The optimum concentration of Al, Ni, Bi and Sn addition has been established. Some tests have been conducted to determine the synergistic effect of the addition of AlNiBiSn to a zinc bath upon the structure and growth kinetics of coatings. The structure of the coatings obtained on steel with low silicon contents and on Sandelin steel as well as their chemical composition have been revealed. It has been established that the addition of AlNiBiSn helps to reduce excessive growth of coating on Sandelin steel. The chemical composition and the structure of the coating on Sandelin steel are similar to the chemical composition and structure obtained on steel with regular silicon contents.

Corrosion Resistance of Zinc Coatings Obtained in High-Temperature Baths

We present the results of investigation of the technology of application of coatings in zinc baths at temperatures different from the standard temperatures of the process of galvanization. The corrosion resistance of the coatings is determined under the action of neutral salt mist and sulfur dioxide in the case of condensation of moisture. With the help of galvanization at elevated temperatures of 540–560°C, it is possible to obtain coatings of constant thickness with improved structure and higher corrosion resistance as compared with the coatings obtained at standard temperatures.

Investigation of the Initial Stage of Hot Dip Zinc Coatings on Iron Alloys with Various Silicon Contents

In this work tests on the course of zinc coating formation on model iron alloys with diversified silicon additions in molten zinc, with short times of contact at the solid-liquid border have been presented. The experiments were carried out at the temperature of 440°C. The assumed time of contact between solid and liquid phases was: 1, 4, 9, 14, 29, 59 seconds. The test stand was designed. The structure and thickness of coatings obtained on steel without silicon, on Sandelin steel and on high-silicon steel was defined. Based on the results we may ascertain that in the first stadium of the galvanizing process the impact of silicon upon the intensity of coating growth is small. Increased reactivity of silicon is already observed after about 29-59 seconds of the process.

Synergistic Influence of the Addition of Al, Ni and Pb to a Zinc Bath upon Growth Kinetics and Structure of Coatings

In this paper the current knowledge about the influence of alloy additions used in galvanizing baths has been analysed. The optimum concentration of Al, Ni and Pb addition has been established. Tests have been conducted to determine the synergistic influence of the addition of AlNiPb in a zinc bath upon the structure and growth kinetics of coatings. The structure and the chemical composition of coatings obtained on steel with low silicon contents and on Sandelin steel have been developed. It has been determined that the synergistic influence of the AlNiPb addition effectively lowers the reactivity of Sandelin steel and it improves zincs flowing off the product surface which results in decreased zinc consumption and better appearance of the coating. The structure of coatings obtained in a Zn-AlNiPb bath on Sandelin steel is similar to the structure of coatings obtained on low-silicon steel.

The Influence of the Chemical Composition of a Zinc Bath on the Growth Kinetics and Structure of Coatings Obtained on B500SP Steel

In the paper the results of tests conducted to determine the synergistic influence of alloy additions to a zinc bath upon the structure and growth kinetics of coatings obtained on reinforcing steel are presented. The structure and the chemical composition of coatings obtained on B500SP steel have been developed. The tests were carried out in Zn-AlNi, Zn-AlNiBi and Zn-AlNiBiSn baths. It has been determined that the additions of Bi and Sn reduce the coating thickness on B500SP reinforcing steel. The growth kinetics of coatings on the tested reinforcing steel - even though the concentration of Si was within the Sebisty range - did not show reversed temperature dependence, which is characteristic of this type of steel.

The structure and growth kinetics of zinc coatings on link chains produced of the 23MnNiCrMo5-2 steel

In the paper the results of tests on obtaining zinc coatings on chains produced of the 23MnNiCrMo5-2 steel of grades C and PW9 have been presented. The growth kinetics of coatings obtained in the traditional galvanizing process at the temperature of 450°C has been established. The structure of coatings obtained on chains of various grades has been developed. The chemical composition of structural components of the coating has be established. It has been determined that the obtained coatings are continuous and they are quite thick. No significant impact of the chain grade upon the structure of coating has been established, however, it has been observed that the thickness of coating slightly decreases as the grade increases.

Influence of Hot-Dip Galvanised Coating Morphology on the Adhesion of Organic Coatings Depending on the Zinc Bath Pb Content and the Postgalvanising Cooling Method

Hot-dip galvanised coatings used either alone or with an organic coating (duplex system) constitute an effective anticorrosion protection. Adhesion between the coating and the zinc substrate plays a vital role in the durability of the duplex system. Conditions of the galvanising process and alloying additives incorporated into the zinc bath influence mechanical and protective properties as well as thickness, structure, and surface morphology of the zinc coatings. The influence of the surface morphology of zinc coatings on the adhesion of organic coatings was studied. The tests were carried out on zinc coatings produced in baths with varying Pb content and by employing various cooling methods after the galvanising process. It was noted that a rapid cooling in water produces zinc coatings with a fine-grain structure, more suitable for paint application compared to the air-cooled ones, with a spangle.

Zinc Coatings Obtained by Hot Dip Method on the High Strength Steel for Link Chains

The 23MnNiCrMo52 steel is used to produce coil chains for the mining industry. The chemical composition of that steel is responsible for the high strength of chains but their corrosion resistance is not sufficient. The chains are delivered as naturally black, treated with anti-corrosion oil or painted. They are not generally protected against corrosion by hot dip zinc coatings due to their specific shape and complex chemical composition of steel. In the paper the authors present the results of tests on obtaining zinc coatings on the 23MnNiCrMo52 steel. The growth kinetics of the coatings has been defined, their structure has been developed and the chemical composition of particular structural components of the coating has been established. It has been determined that the obtained coatings are continuous and uniform and their morphology depends on the chemical composition of the galvanized steel.