CN105132853A - Hard high-damping coating preparation process used for surface of high-temperature damping part - Google Patents

Abstract

The invention discloses a preparation process for a hard high-damping coating on the surface of a high-temperature damping part. The process first decontaminates the surface of the workpiece; then roughens the surface of the workpiece by surface sandblasting; then preheats the workpiece after sandblasting; sprays the surface of the workpiece by low-pressure plasma spraying, and the coating material system It is any one of NiCr-based superalloy coating, FeCr-based ferromagnetic coating and YSZ ceramic coating; the coating is subsequently vacuum annealed. The coating composite structure prepared by this process not only has high damping performance, but also has high mechanical properties, can withstand large stress, and has a wide range of temperature applications. The damping performance of this damping structure is significantly higher than that of other coatings. Block damping material. The coating is uniform, the bonding strength with the substrate is high, and it has the characteristics of low implementation cost, easy operation, high yield rate and high product comprehensive performance.

Description

A preparation process for hard high damping coating on the surface of high temperature damping parts

technical field

The invention relates to the preparation of a damping coating, in particular to a preparation process for a hard high damping coating used on the surface of a high temperature damping part.

Background technique

Vibration control and noise suppression of dynamic systems are extremely desirable in the design of aviation, aerospace, ships, military and other industries. Excessive vibration and noise may cause structural damage, environmental degradation, affect the normal work of airborne equipment, affect combat effectiveness, and even cause catastrophic damage. In most cases, material strength and damping performance are contradictory. In fact, the commonly used materials for aero-engine blades such as aluminum alloy, martensitic stainless steel, titanium alloy and other high-temperature alloys have poor damping performance due to excessive consideration of strength factors. Poor, the damping performance Q ^-1 is often less than or only in the order of 10 ^-3 . For many dynamic systems in practical applications, like blades, their strength, dynamic and static mechanical properties, and hydrodynamic characteristics must be considered. A high damping hard layer is introduced on the surface to suppress the vibration and noise of these structures.

The hard coating will not affect the mechanical properties and hydrodynamic shape design of the base material; the coating can spread all over the structure, which helps to suppress the dynamic response of the structure; more importantly, the coating itself will bring Incorporate a composite damping structure (defects such as interface and void cracks), and use the composite structure introduced by the coating to improve the damping performance of the structure.

Existing damping coatings are generally polymer materials, although the damping performance can be significantly improved, but they cannot withstand high temperatures. The thickness of the coating cannot be determined. If the coating is too thick, there are too many internal defects and the bonding force is poor. Not only can the damping performance not be fully exerted, but the peeling of the coating will lead to increased surface wear of the workpiece, and ultimately aggravate the damage of the workpiece.

Contents of the invention

In order to solve the above-mentioned problems in the prior art, the present invention utilizes the introduction of a coating composite structure to improve the damping performance of the structure, and especially develops a preparation process for a hard high-damping coating on the surface of high-temperature damping parts. Specifically, the low-pressure plasma spraying method is used to spray a hard coating on the metal substrate, and the preparation process is optimized to obtain high comprehensive damping performance. This composite structure with a hard high damping coating can be used under high temperature and harsh conditions, that is, to meet the mechanical properties and heat resistance, not only has high damping, but also can withstand high temperature corrosion environment, suitable for workpieces operating at high temperature, Suitable for use in dynamic systems such as blades.

The technical solution adopted by the present invention is: a preparation process for a hard high-damping coating on the surface of a high-temperature damping part, which is characterized in that: the damping coating is prepared by a low-pressure plasma spraying method, and the preparation process has the following steps:

Step 1. Carry out decontamination treatment to the workpiece surface;

Step 2. roughen the surface of the workpiece by surface blasting;

Step 3. Preheating the workpiece after sandblasting;

Step 4. The workpiece surface is sprayed by the low-pressure plasma spraying method, and the coating material system is: any coating in NiCr series superalloy coating, FeCr series ferromagnetic coating and YSZ ceramic coating;

Step 5. Subsequent vacuum annealing treatment is performed on the coating.

The beneficial effects produced by the present invention are: the coating composite structure prepared by this process not only has high damping performance, but also has high mechanical properties, can withstand relatively large stress, and has a wide range of temperature applications. The damping performance of the structure is significantly higher than that of its bulk damping material. The coating of the invention is uniform, has high bonding strength with the substrate, has the characteristics of low implementation cost, simple and convenient operation, high yield rate and high product comprehensive performance.

The advantages of the present invention are:

1. The composite structure is composed of a coating and a substrate. Compared with non-ferrous metals with high damping properties such as MnCu alloys and Ti alloys, this coating structure has a lower cost. At the same time, the damping performance is significantly increased compared to the same material of the block.

2. Compared with polymer coating materials, it has higher material strength, modulus, high temperature resistance and creep resistance. Increased the applicable temperature range of the workpiece.

3. Compared with the method of damping structure and shock isolation, the coating treatment maintains the high mechanical properties and hydrodynamic properties of the substrate, and does not increase the quality of the dynamic system, which is conducive to the increasingly sophisticated development of mechanical instruments.

4. The coating composite structure can increase the natural vibration frequency of the system, preventing the harm caused by the resonance that is the most damaging to the material.

5. The thickness of the coating can maintain excellent damping performance, avoiding excessive stress and poor bonding state. Therefore, it has better comprehensive performance.

Description of drawings

Fig. 1 is the temperature effect comparison curve diagram that adopts the coating composite structure damping performance Q ^-1 prepared by the present invention,

Among them, ■ means 1Cr18Ni9Ti substrate; ▲ means NiCrAlY coating; ● means FeCrMo coating; ★ ZrO ₂ ceramic coating.

Detailed ways

The present invention is described in further detail below:

1. First clean the workpiece in an ultrasonic cleaner with alcohol as a solvent. The concentration of the alcohol solvent is 95%, and the cleaning time is 20-25 minutes (generally 20 minutes). Use the alcohol solvent to remove the oil on the surface of the substrate.

2. Use a sandblasting machine to spray the surface of the workpiece, the sandblasting granularity is 250-320 mesh; the sandblasting angle is perpendicular to the workpiece surface; the sandblasting pressure is 0.6-0.7MPa (generally set to 0.6MPa). Since the thermal spraying substrate and the coating are generally mechanically bonded, the working layer of the substrate is sandblasted (it can also be polished), which is conducive to increasing the bonding surface area and enhancing the interface bonding strength between the substrate and the coating.

3. The temperature for preheating the workpiece after sandblasting is 180-200°C (generally set at 190°C); the preheating time is 1-2mim (generally set at 1.5mim). Due to the difference in thermal expansion coefficient between the workpiece and the coating, the substrate is prone to generate large thermal stress during thermal spraying, and the generation of internal stress will cause the coating to peel off. As a result, not only the damping performance cannot be enhanced, but the parts are damaged. In order to prevent the harm caused by internal stress, it is necessary to preheat.

4. Use plasma spraying equipment to spray the surface of the workpiece, and the process parameters are set as: voltage 55-56kv; current 550-580A; argon 57-62L/min; hydrogen 18-22L/min; powder feeding rate 20-30g/ min. The thickness of the coating is 0.09-0.15mm.

5. Use a vacuum annealing furnace to conduct vacuum annealing treatment on the coating at a temperature of 650-750°C (generally set at 700°C), and the processing time is 90-120min (generally set at 100min), and the furnace body is naturally cooled to room temperature. Stress-relief annealing is performed to reduce the residual stress after the transformation of the coating and matrix structure, and promote the metallurgical bonding between the matrix and the coating.

Example 1: NiCrAlY coating is selected in the NiCr superalloy coating, and the NiCrAlY coating is sprayed on the surface of the workpiece using GP-80 plasma spraying equipment. The alloy composition accounts for the mass percentage (wt%) of the NiCrAlY coating: Cr: 16 ; Al: 6; Y: 0.5; Ni: balance. Voltage 55-60V, current 550-580A, argon gas 60L/min, hydrogen gas 20L/min, powder feeding rate 20g/min.

Embodiment 2: FeCrMo coating is selected among FeCrMo ferromagnetic coatings, and GP-80 plasma spraying equipment is used to spray FeCrMo coating on the surface of the workpiece. The alloy composition accounts for the mass percentage (wt%) of FeCrMo coating: Cr: 16 ; Mo: 3; Fe: balance. Voltage 58-60V, current 550-570A, argon gas 60L/min, hydrogen gas 20L/min, powder feeding rate 30g/min.

Embodiment _three : select ZrO2 ceramic coating in YSZ ceramic coating, adopt GP _- 80 type plasma spraying equipment to spray ZrO2 ceramic coating _on workpiece surface, ceramic composition accounts for ZrO2 ceramic coating mass percentage (wt%) is : Y ₂ O ₃ : 8, ZrO ₂ : balance. Voltage 55-60V, current 550-580A, argon gas 60L/min, hydrogen gas 20L/min, powder feeding rate 20g/min.

The devices used in the above embodiments are all known devices in the industry. The microstructure of the coating prepared by the above method shows that there is an obvious interface between the substrate and the coating, and there are many voids inside the coating. High porosity is one of the important structural features of plasma coatings, and its value is about 4.8-33%. These pores will become one of the higher sources of internal friction under vibration loads. As the spray particles overlap each other during the deposition process, some interlayer interfaces are formed inside the coating.

The damping performance was tested with a dynamic mechanical thermal analyzer. The damping performance of the coating at room temperature is shown in Table 1. The test frequency was 1 Hz and the sample strain was 2×10 ^-4 . The damping performance is significantly improved. The average damping performance Q ^-1 values of the NiCrAlY coating, FeCrMo coating and ZrO ₂ coating structure are 0.0095, 0.0079 and 0.0091, respectively, and the damping value of the substrate 1Cr18Ni9Ti stainless steel 0.0041 has been greatly improved. Among the _three coatings, the highest average dynamic modulus is the ZrO2 coating, whose structural dynamic modulus is about 160GPa. Among the above coating systems, the ZrO ₂ coating structure has excellent damping performance and dynamic mechanical properties.

Table 1 Dynamic modulus E and damping performance Q ^-1 of three coating composite structures at room temperature

1Cr18Ni9Ti 1Cr18Ni9Ti+NiCrAlY 1Cr18Ni9Ti+FeCrMo 1Cr18Ni9Ti ₊ ZrO2 Q ^-1 0.0041 0.0095 0.0079 0.0091 E(GPa) 201 123 130 160

As shown in Figure 1, the comparison curves between the damping temperature effect of each coating structure and the damping characteristics of the substrate and the coating itself, the test frequency is 1 Hz, the heating rate is 5 °C/min, and the sample strain is 2×10 ^-4 ; the NiCrAlY coating is Cantilever mode. It can be seen from the figure that the internal friction of each coating structure is significantly higher than that of the 1Cr18Ni9Ti substrate, especially in the lower temperature region (room temperature to 250°C); in addition, the damping characteristics of each coating structure have obvious temperature peak effects, that is, internal friction appears in the temperature spectrum The internal friction peaks of NiCrAlY coating, FeCrMo coating and ZrO ₂ coating appear at about 210 °C, 250 °C and 340 °C, respectively. In a large temperature range, the damping performance of the coating structure is significantly improved. The appearance of these internal friction peaks means that the coating structure can be used in high temperature environments and has great use value.

The embodiment of the invention uses 1Cr18Ni9Ti stainless steel as the base material, which has good corrosion resistance, heat resistance, low temperature strength and mechanical properties. After proper treatment, a certain modulus, toughness and wear resistance can be obtained, and the material source is convenient. Compared with non-ferrous metals, it has low cost.

The damping coating was prepared by low-pressure plasma spraying (LPPS) method. The base material has a high dynamic modulus to maintain the required mechanical properties of the blade, and the coating material is made of metal alloy or ceramic material with high damping performance, so that it can withstand the harsh environment of high temperature and high stress. Improve the overall damping performance of the composite system, with high damping characteristics while maintaining a high dynamic modulus. The thickness of the coating is 0.09-0.15mm. While obtaining the maximum damping performance, the coating is in a good bonding state and is not easy to peel off.

Claims (10)

1. for the hard high damping preparation technology of coating on high temperature damping piece surface, it is characterized in that: adopt low-voltage plasma spraying method to prepare damping coatings, its preparation technology has the following steps:

Step one. abatement processes is carried out to workpiece surface;

Step 2. adopt surface sand-blasting process to carry out alligatoring to workpiece surface;

Step 3. preheating is carried out to the workpiece after sandblasting;

Step 4. adopt low-voltage plasma spraying method to spray workpiece surface, coated material system is: any one coating in NiCr system alloy coating at high temperature, FeCr system ferromegnetism coating and YSZ ceramic coating;

Step 5. follow-up vacuum annealing process is carried out to coating.

2. a kind of hard high damping preparation technology of coating for high temperature damping piece surface according to claim 1, is characterized in that: be first that solvent cleans in ultrasonic cleaning instrument with alcohol by workpiece; Spirit solvent concentration is 95%, and scavenging period is 20-25min.

3. a kind of hard high damping preparation technology of coating for high temperature damping piece surface according to claim 2, is characterized in that: adopt sandblast machine to spray workpiece surface, sand size is 250-320 order; Sandblasting angle is perpendicular to workpiece surface; Blasting pressure is 0.6-0.7MPa.

4. a kind of hard high damping preparation technology of coating for high temperature damping piece surface according to claim 3, is characterized in that: the temperature of the workpiece after sandblasting being carried out to preheating is 180-200 DEG C; Warm up time is 1-2min.

5. a kind of hard high damping preparation technology of coating for high temperature damping piece surface according to claim 4, is characterized in that: employing plasma spraying equipment to the processing parameter setting that workpiece surface sprays is: voltage 55-58kv; Electric current 550-580A; Argon gas 57-62L/min; Hydrogen 18-22L/min; Powder feeding rate 20-30g/min.

6. a kind of hard high damping preparation technology of coating for high temperature damping piece surface according to claim 5, is characterized in that: the thickness of coating is 0.09-0.15mm.

7. a kind of hard high damping preparation technology of coating for high temperature damping piece surface according to claim 6, it is characterized in that: the temperature adopting vacuum annealing furnace to carry out vacuum annealing process to coating is 650-750 DEG C, treatment time is 90-120min, and body of heater naturally cools to room temperature.

8. a kind of hard high damping preparation technology of coating for high temperature damping piece surface according to claim 1, it is characterized in that: select NiCrAlY coating in NiCr system alloy coating at high temperature, shared by alloying constituent, NiCrAlY coating quality per-cent is: Cr:16; Al:6; Y:0.5; Ni: surplus.

9. a kind of hard high damping preparation technology of coating for high temperature damping piece surface according to claim 1, it is characterized in that: select FeCrMo coating in FeCr system ferromegnetism coating, shared by alloying constituent, FeCrMo coating quality per-cent is: Cr:16; Mo:3; Fe: surplus.

10. a kind of hard high damping preparation technology of coating for high temperature damping piece surface according to claim 1, is characterized in that: select ZrO in YSZ ceramic coating ₂ceramic coating, ZrO shared by ceramics component ₂ceramic coating mass percent is: Y ₂o ₃: 8, ZrO ₂: surplus.