A kind of preparation method and process of titanium fireproof coating

       The invention belongs to anti-titanium fire coating

Technical field:

, specifically relates to a preparation method of a titanium fireproof coating.

Background technique:

: Titanium alloy has the advantages of high strength, low density and high melting point, so it is widely used in compressor casings, rotor discs, rotor blades and other components of aviation gas turbine engines to reduce the weight of the engine and improve the thrust-to-weight ratio. However, ordinary titanium alloys will burn at a certain temperature, pressure and airflow speed, and the combustion will spread rapidly and damage engine components, thus restricting the application of titanium alloys in aircraft engines. In order to further improve the efficiency of the engine, higher requirements are placed on the sealing performance of the casing in the combustion chamber. Titanium alloy rotor blades rotate at high speed at high temperature. Due to thermal expansion or centrifugal force generated by their own mass, the blades are elongated. When they contact the inner wall of the casing, there is a danger of titanium fire. The anti-titanium fire-resistant coating is expected to solve the above problems. During operation, a large number of micro-cutting edges on the hard particles in the coating scrape the soft coating on the inner wall of the casing to form furrow-shaped groove marks, which not only plays a good sealing role, but also has a good sealing effect. It can avoid the occurrence of titanium fire. However, the existing titanium fireproof coatings generally have shortcomings such as poor impact resistance, weak bonding with the matrix, or significantly reduced matrix fatigue performance, which cannot meet the current needs. Therefore, it is necessary to develop coating materials with higher performance and preparation technology. Technical realization elements: the purpose of the present invention is to overcome the deficiencies of the prior art and provide a preparation method of a titanium fireproof coating. The invention is realized by the following technical scheme: a preparation method of titanium fireproof coating: continuous thin strip-shaped ti-37.5zr-15cu-10ni base amorphous alloy is selected as brazing material, and cubic nitrogen is selected as hard wear-resistant particle Boron CBN particles are prepared, and the cubic boron nitride CBN particles are subjected to chemical plating ni treatment. The mass ratio of CBN particles to solder is 8:2 to 7:3. The preparation steps are as follows: 1. Vacuum sandblasting the tip of the blade To remove the oxide film on its surface; 2. Pre-place a thin ribbon of solder on the tip of the blade, so that the solder wraps the tip of the blade that needs to be coated with an anti-titanium fire coating. The boron nitride cbn particles are mixed, and then uniformly coated on the brazing filler metal; 3. In a high vacuum environment greater than or equal to 8×10-4pa, the rotor tip is locally heated by an intermediate frequency induction coil to keep the heating temperature at 840 -850 ℃ for a certain time, so that the solder can be completely melted. After the solder is melted, it will be combined with the titanium alloy matrix. At the same time, the cbn particles are immersed in the solder under the surface adsorption, and the solder will be naturally cooled in a high vacuum environment. , forming an anti-titanium fire coating. In the above technical solution, the cubic boron nitride cbn powder contains niwt.30%. In the above technical solution, the volume ratio of the organic binder to the cubic boron nitride cbn powder containing ni is 1:10. In the above technical solution, the brazing filler metal is a continuous thin strip-shaped ti-37.5zr-15cu-10ni-based amorphous alloy with a thickness of 50 μm. In the above technical solution, the mass ratio of the cbn particles to the brazing filler metal is preferably 8:2. The advantages and beneficial effects of the present invention are as follows: 1. Cubic boron nitride (cbn) is a multifunctional material integrating many excellent properties, and its comprehensive properties even exceed diamond, and it has high hardness, high thermal stability and high chemical inertness. CBN particles are irregular angular, with many sharp edges on the surface, which can be used as a hard wear-resistant phase. The titanium fireproof coating prepared by the present invention adopts the cbn particles of different particle sizes and the metal bonding phase to prepare the titanium fireproof coating, wherein the large particles play a main grinding role, while the small particles are used to strengthen the coating, improve the hardness and hardness. Impact resistance, thus ensuring the high hardness, high wear resistance, high impact resistance, high temperature oxidation resistance and high flame retardancy of the titanium fireproof coating. 2. The selection of the metal bonding phase (that is, the solder) needs to comprehensively consider the following requirements: ① The melting point should be lower than the phase transition temperature of the titanium alloy substrate (the nature of the titanium-based alloy determines the main temperature of the metal bonding phase process). The limitation is due to the important changes in its structure and properties at the so-called "above β transformation", that is, above the critical α←→β transformation temperature. Therefore, when processing titanium-based alloy blades The above factors should be considered. According to their main composition phases at room temperature, titanium alloys can be basically divided into three categories: α and near α alloys, α/β alloys, and β alloys. When titanium-based alloys are combined with bonding, The effect on each type of titanium alloy is different, and the most important is the nature of the new phase formed by the reaction between the titanium-based alloy matrix and the binder phase. Most of the new phases formed are brittle intermetallic compounds, such as tixniy and tixcuy, Their formation has a negative effect on the entire connection. Therefore, in general, melting the binder phase at a temperature below the β-transformation temperature can retain and obtain a titanium alloy with excellent mechanical properties. Titanium fireproof coating); ② It has good wettability with titanium alloy substrate and cbn particles; ③ it can meet the requirements of mechanical strength of the coating. The present invention selects continuous thin strip-shaped ti-37.5zr-15cu-10ni-based amorphous alloy as the metal bonding phase (that is, solder). These amorphous, uniform and soft thin foils have excellent melting and wetting characteristics, and The titanium alloy base material has good compatibility, and can accurately pre-place the brazing filler metal at the tip of the blade with a minimum amount, which can realize the mechanical properties of the brazed joint that cannot be achieved with powdered or clad ribbon brazing filler metals; this alloy The melting temperature of the titanium alloy is about 840 °C, which is lower than the β phase transition temperature of most titanium-based materials. Therefore, the preparation temperature of the titanium alloy preparation method of the present invention is between 840 °C and 850 °C, which can not only ensure the complete melting of the solder, but also Under the β-transition temperature of titanium-based materials, it will not affect the performance of the matrix itself (matrix fatigue performance), which provides a strong guarantee for the titanium alloy titanium fireproof coating that can obtain excellent mechanical properties.