Copper-based bronze alloy with surface hardened by boronizing process

Abstract

The invention relates to a copper based bronze material (1), characterized in that it comprises a copper based bronze material (1) which has been boronizing treated to improve its performance by increasing its wear and corrosion resistance.

Description

[0001] COPPER-BASED BRONZE ALLOY WITH SURFACE HARDENED BY BORONIZING PROCESS

[0002] Technical Field

[0003] The invention relates to a copper-based bronze alloy, which is surface hardened by boronizing to improve wear and corrosion resistance.

[0004] The present invention relates to a bronze alloy in which a protective barrier surface is formed for hard, durable and anti-corrosion properties, the performance of which is improved by increasing the wear and corrosion resistance of copper-based bronzes by coating their surfaces with boronizing.

[0005] Prior Art

[0006] Bronzes are historically known as copper alloys with tin as the main alloying element. Nowadays, bronzes are usually composed of containing approximately 80% copper and 10-20% one or more elements. These alloys may contain higher proportions of metals such as tin, aluminum, nickel, iron, cobalt, manganese, zinc, along with small amounts of non- metals such as arsenic, silica and phosphorus. Depending on the elements added, bronzes can be grouped for specific applications such as Leaded Bronze, Aluminum Bronze, Nickel Aluminum Bronze, Phosphorus Bronze and Manganese bronze.

[0007] Bronze alloys have become one of the most useful engineering materials for many industrial applications because they exhibit purpose-built strength and corrosion and wear resistance properties depending on the elements they contain. These alloys are widely used in all bearings, slides, bushings, gears, etc. bronze machine equipment, wear-resistant machine parts, aircraft landing gear material, press bearings and slides, ship propellers and gear making, and pipe bending molds.

[0008] Bronzes are one of the best alloys for industrial applications where high corrosion and wear resistance is critical. Despite their excellent wear and corrosion resistance properties, they are subject to wear-corrosion damage at high loads and in more active environments. Therefore, there is a constant quest to extend the life of bronze alloys by improving their wear and corrosion resistance. Boronizing is a thermochemical surface hardening technique performed by diffusion of boron atoms to form hard boride compounds on the surface.

[0009] In this process, boride compounds are formed on the surface of the material at high temperature, resulting in a hard layer of a certain thickness. The most important advantages of this method are that this boride layer has high hardness, high corrosion and oxidation resistance, low coefficient of friction at high temperature. The main parameters affecting the properties of the boride layer formed on the bronze surface are the duration and temperature of the boronizing process, the boron concentration of the boron source used and the chemical composition of the substrate.

[0010] Various methods are currently used to improve the wear and corrosion properties of copper-based bronzes. These techniques are:

[0011] 1) Thermal Spraying Process:

[0012] It is a group of coating technologies in which molten or heated materials are deposited on a substrate surface. Several methods are available, including flame spraying, plasma spraying and electric arc spraying. These methods use intense heat sources such as combustion flames, plasma arcs or electric arcs to melt or partially melt the raw material material (metal wires, ceramic powders, etc.). The molten / heated particles are then pushed down into the substrate and created layer by layer to form a coating.

[0013] 2) Selective Laser Melting:

[0014] Selective laser melting is an additive manufacturing method in which metallic powders are melted together with the help of a high-intensity laser to form the desired 3D objects.

[0015] The above-mentioned 2 methods have been used to create a modified surface layer on the surface of the bronze alloy and / or to increase its wear and corrosion resistance. No studies on the formation of a layer on the surface with Boron in bronze alloys have been found in the literature and patents. Only by adding B4C to the powder mixture by Electron Beam Additive Manufacturing method, material production was carried out by sintering. No method of improving surface properties by boronizing, a diffusion-controlled process, has been used.

[0016] The following patents were found in the patent search conducted in relation to the Prior Art. In the Chinese patent application CN106756213A; the production of a composite material consisting of tin bronze powder, boron nitride and reinforcement phase as copper base material has been realised to provide high resistance to wear of copperbased tin bronze. No diffusion-controlled boronizing surface treatment is available. Bornitride-reinforced composite made by powder metallurgy.

[0017] The Chinese patent application CN117448735A mentions a boronizing method for martensitic steels. There is no mention of any copper-based bronze materials.

[0018] In the patent application CN108315688A ; while mentioning the boronizing of sintered materials, the boronizing of bronze materials, which is our invention, is not mentioned. However, the bronze material in our invention is not sintered and is produced by casting method.

[0019] German Patent No. DE4443914A1 mentions the thermochemical surface treatment of steel parts in fluidized bed and mentions the boronizing process on steel surfaces.

[0020] Purposes of the Invention

[0021] The purpose of the invention is to provide a bronze material that is resistant to wear and corrosion by changing a layer on the surface of the copper-based bronze material as a result of the boronizing process.

[0022] A purpose of the invention is to boronize the surfaces of these bronzes used in applications such as bearings, slides, bushings and aircraft landing gear, which has the potential to make a significant impact on the literature and industry.

[0023] The invention aims to enable the production of more reliable and durable products in various industrial fields and applications by increasing the durability and performance of such bronze materials.

[0024] Another important purpose of the invention is to reduce the time of the boronizing process, to reduce the carbon footprint, to reduce the energy used and the cost spent.

[0025] Another purpose of the invention is to increase the wear resistance of the bronze material. Bronze materials are often subject to friction and wear. With a surface formed by the diffusion of boron atoms, it is possible to increase the durability of the material and thus to produce a product with long durability. Another purpose of the invention is to improve the corrosion properties of bronze by boronizing, especially in humid or chemically aggressive environments.

[0026] Another purpose of the invention is to extend the life of bronze materials by boronizing and to reduce the need for maintenance, thus saving maintenance costs.

[0027] Another purpose of the invention is to make the surfaces of bronze materials coated with boronizing stronger and more durable, so that they can withstand more extreme conditions.

[0028] The invention aims to improve the performance of bronze products. Boronizing improves the performance of bronze materials, especially in applications where wear and corrosion are of concern.

[0029] The invention can offer many potential applications across a range of industrial sectors, such as marine, automotive, aerospace, building materials and more.

[0030] Figures to Help Understand the Invention

[0031] Figure-1 Representative view of the boronizing process on copper-based material.

[0032] Reference Numbers

[0033] 1- Copper-based bronze material

[0034] 2- Boronizing powder

[0035] 3- Tank

[0036] 4- Protective Gas

[0037] 5- Gas pipe

[0038] 6- Furnace

[0039] 7- Heating element

[0040] 8- Furnace button

[0041] 9- Control panel

[0042] 10- Boronized Bronze material

[0043] A-Sandblasting B-Polishing C- Refining Detailed Description of the Invention

[0044] Copper-based bronze material (1) is a bronze material with a high copper concentration whose surface is to be boronized. In order to prepare the surface of the material for boronizing, surface cleaning processes are first applied. These processes include sandblasting (A), polishing (B) and refining (C).

[0045] Sandblasting (A) process is applied to remove unwanted materials such as dirt, rust, paint residues on the surface of the material. In this process, sand or another abrasive is used under high pressure to remove unwanted layers from the surface.

[0046] Polishing (B) can be applied to remove roughness on the surface and to obtain a smooth surface. This is usually done to make the surface more glossy and to ensure better adhesion.

[0047] On the other hand, the refining (C) process is applied to remove oil, dirt and other contaminants from the surface. This is usually carried out using chemical solvents or special cleaning agents.

[0048] Boronizing powder (2) is used in the boronizing process. These boronizing agents are used to increase the effectiveness of the boronizing process and to ensure the formation of a boron coating on the surface of the bronze material. Boronizing powder (2) refers to a mixture containing the boron element. Boron agents that can be used in this invention:

[0049] -5% B4C, 90% SiC, 5% KBF4

[0050] -85% B4C, 15% Na2CO3

[0051] -95% B4C, 5% Na2B4O7

[0052] -84% B4C, 16% Na2B4O7

[0053] -Amorphous boron (95-97%), (3-5%) KBF4

[0054] -95% Amorphous Boron, 5% KBF4

[0055] -79% B4C, 16% Na2B4O7, 5% KBF4

[0056] -60% B4C, 5% B2O3, 5% NaF, 30% iron oxide

[0057] -(40-80%) B4C, (20-60%) Fe2O3

[0058] -50% Amorphous Boron, 1% NH4F.HF, 49% AI2O3 -100% B4C

[0059] -20% B4C, 5% KBF4, 75% Graphite

[0060] - Amorphous boron

[0061] -Ferrobor or boron agents with different compositions can be used.

[0062] Sealed Boronizing Tank (3); The sealed tank where the boronizing process will take place is a critical component for this process. The lid of the tank usually has a screw tightening system. The tank and cover must be made of stainless steel or other high temperature resistant steel. The properties of these materials should include high temperature resistance and the ability to withstand distortion.

[0063] The inside of the tank (3) should be cleaned and dried before surface hardening by boronizing. If there are residues inside the tank, they are cleaned using sandpaper with a mesh size of 240-800 mesh, washed with alcohol and dried with compressed air. After the cleaning process is completed, boron agent is added to a certain part of the tank (3) and the material is placed on this agent. Pour boron agent all over the material and cover the surface of the material with boron agent up to 4 cm below the lid.

[0064] Copper powder or shavings are then added to the empty part of the tank (3) on top of the boronizing powder (2). This powder is used as a cover material and prevents oxygen leakage and oxidation during high temperature boronizing. After all these steps are completed, the screw cap of the tank (3) is tightly closed and the material is disconnected from the outside by covering the cap with high temperature resistant silicone and / or other sealing material.

[0065] These surface cleaning operations are important to prepare the surface of the material for the boronizing process. A clean surface improves the efficiency of the boronizing process and increases the diffusion rate, Protective Gas (4); Since boron has a high affinity for oxygen, it is important to use protective gas (4) to prevent oxidation during the boronizing process. These gases prevent oxygen from reaching the material in the furnace where the boronizing process takes place at high temperature.

[0066] Inert gases such as pure argon, pure nitrogen or a mixture of argon and nitrogen with hydrogen can be used during the boronizing process in the sealed tank (3). These gases prevent oxidation that may occur on the surface of the material during boronizing and thus increase the effectiveness of the boronizing process. Gas pipe (5); Gas pipe (5) made of steel material is used to prevent oxidation and to transport the protective gas (4), called inert gas, into the furnace (6). The steel pipe (5) ensures that the gas (4) is safely transported into the furnace (6) and helps to keep it under control.

[0067] Furnace (6) is the environment where the boronizing process will be performed. The tank (3), in which boronizing powder (2) agents and bronze material (1) are placed and insulated, is placed in the furnace (6) and the door of the furnace (6) is closed. Then the furnace button (8) is pressed and the temperature of 850-1050°C and 2-10 hours are set on the control panel (9), where the boronizing heat treatment will be performed, and the process starts. From the beginning to the end of the process, inert gas, i.e. protective gas (4), flows into the environment.

[0068] The heating element (7) is preferably a heating element, preferably a resistance or other type of heater. Heat flow is provided by converting electrical energy into temperature inside the furnace (6) and it is ensured that it reaches the temperature at which the boronizing process will be carried out.

[0069] Furnace button (8); Switches the furnace (6) on and off. Control panel (9) is the control panel where the temperature and time of the boronizing process will be entered.

[0070] Boronized Bronze material (10); 850-1050°C °C degree the tank (3), which is cooled in the furnace after the boronizing process performed at 2-10 hours intervals, is then taken out and the cover of the tank is opened. The powders are poured into an empty container and the surface coated bronze material (1) is taken out.

[0071] As a result of the examinations, it was observed that a hard layer with an average thickness of 25 pm was formed on the surface consisting of beta (P) and hard kappa (x) phase and boride. This hard layer makes bronze an ideal structure for wear resistance. The newly created surface increased the surface hardness of the bronze by 300% - 500%, while no decrease in matrix hardness was observed. In addition, as a result of the wear tests, it was measured that the wear resistance of bronze increased by 500% and the coefficient of friction decreased significantly.

[0072] Among the advantages of this invention is the increased wear resistance of the surface of the bronze material, making it more durable. Investigations show that this increase in hardness and wear resistance are mutually reinforcing. According to known systems, the present invention is a thermochemical diffusion process in which boron atoms diffuse (diffuse) to the surface of the bronze component placed inside the tank (3), which is a closed container filled with a boron-emitting powder package. The component is heated at high temperatures (typically 850-1050°C) for several hours and the coating process is completed. Other processes, such as thermal spray and selective laser melting, are applied by spraying or melting specific powders onto the surface of the material. But while these methods can be more expensive and complex, boronizing is a more feasible and simple process. In the light of these disclosures, our invention provides an effective, economical and practical method for improving the durability of bronze materials.

[0073] This invention offers a process that does not require the use of complex devices such as thermal spray and selective laser melting, reducing production costs and increasing viability. Furthermore, current techniques, i.e. the thermal spray method, generally cannot provide a uniform coating of the material as a whole. However, with the method we have invented; the entire material is homogeneously changed as a layer with boronizing surface hardening. Selective laser melting has lower industrial applicability and requires high costs. It is usually used as a powder mixture in material production. While these methods usually fail to form a hard boride layer on the surface, our invention creates a hard boride layer on the surface by thermochemical treatment. In the light of these disclosures, our invention is different from other methods as a thermochemical process and an efficient and effective option is presented to increase the resistance of bronze materials against wear and corrosion.

[0074] Industrialists are finding it difficult to apply processes such as thermal spray and selective laser melting to meet their demand for bronze materials with high wear and corrosion resistance. While these processes are generally applicable at the laboratory level, they are not suitable for industrial applications. However, surface hardening by boronizing can be applied to all materials, from small to large, with complex shapes.

[0075] However, in the present invention there is no change in any tolerance on the surface of the material. Instead of a layer of increasing thickness on the surface, the main dimension of the material does not experience any dimensional change through diffusion.

[0076] This method offers an effective solution for the production of bronze materials (1) with high wear and corrosion resistance required by industry. In this way, industrialists can both reduce their costs and facilitate their production processes (In this way, industrialists can both reduce their production costs and facilitate their production processes). For this reason, surface hardening of bronzes by boronizing is a solution that can meet the wide- ranging needs of the industry. In this study, a homogeneous boride layer thickness of 5-24.7 pm is obtained in the boronizing process performed at 850-1050 °C temperatures for 2-10 hours. As the thickness of this layer increases, cracks and material losses occur on the material surface. This is due to the difference between the thickness of the boride layer and the mechanical compatibility of the material. Thick boride layers cause stress concentrations on the surface of the material and hence the formation of microcracks. Over time, these micro-cracks develop into larger cracks, causing fragments to break away from the material surface. The optimum temperature and time in this study increase the toughness and adhesion of the boride thickness to the surface.

[0077] In the boronizing powders used, the finer the powder size (5-45p), the greater the surface area in contact with the material during the boronizing process and the more effective the diffusion. This results in a more homogenous boride layeron the bronze material, enhancing mechanical properties such as hardness and wear resistance.

[0078] The larger surface area of fine boronizing powders allows for a more homogeneous and dense penetration of boron atoms into the material surface. This shortens the diffusion paths of boron atoms on the surface and increases the diffusion rate. Larger powder particles cannot have the same effect due to limited surface contact, which slows down the diffusion process and requires higher temperatures. Performing the boronizing process at lower powder sizes saves energy.

[0079] The addition of compounds containing graphite or silicon carbide in the boronizing agents, due to the high heat conductivity of these compounds, ensures a homogeneous distribution of temperature at the material and powder interface, easier diffusion and a more homogeneous boride layer.

[0080] In this study, the addition of exothermic chemicals such as KAIF3 and K3AIF6 to boron powders causes the powders to heat up faster and the boronizing process to proceed faster. This allows the boronizing process temperature to be reached more quickly and the boronizing process to be carried out in a shorter time.

Claims

CLAIMS1- The invention relates to a copper based bronze material (1), characterized in that it comprises a copper based bronze material (1) which has been boronizing treated to improve its performance by increasing its wear and corrosion resistance.2- The copper-based bronze material (1) according to claim 1 , characterized in that; bronze material (1) has a homogeneous boride layer treated at 850-1050 °C for 2-10 hours to prevent cracking and material loss.3- The copper-based bronze material (1) according to claim 1 , characterized in that the boronizing powder size is between 5 and 45p in order to increase the surface area in contact with the material in the boronizing process and to ensure effective diffusion; boronizing powder size is between 5 and 45p fine.4- The copper-based bronze material (1) according to claim 1 , characterized in that it contains graphite or silicon carbide with high heat conductivity (x2_) to ensure homogeneous temperature distribution, easy diffusion and a homogeneous boride layer at the material and powder interface (x1_).5- The copper-based bronze material (1) according to claim 1 , characterized in that it contains the exothermic chemicals KAIF3 and K3AIF6 incorporated into the powders to ensure rapid heating of the powders and rapid progress of the boronizing process.6- The copper-based bronze material (1) according to claim 1 , characterized in that the boronizing powder (2) contains 5% B4C, 90% SiC, 5% KBF4; 85% B4C, 15% Na2CO3; 95% B4C, 5% Na2B4O7; 84% B4C, 16% Na2B4O7; Amorphous boron (95-97%), (3-5%) KBF4; 95% Amorphous Boron, 5% KBF4; 79% B4C, 16%; Na2B4O7, 5% KBF4; 60% B4C, 5% B2O3; 5% NaF, 30% iron oxide; (40- 80%) B4C, (20-60%) Fe2O3; 50% Amorphous Boron, 1 % NH4F.HF, 49% AI2O3; 100% B4C; 20% B4C, 5% KBF4, 75% Graphite.7- The copper-based bronze material (1) according to claim 1 , characterized in that the copper-based bronze material (1) contains a bronze material (1) which is subjected to a sandblasting (A) process by removing unwanted substancessuch as dirt, rust, paint residues on the surface of the copper-based bronze material (1).8- The copper-based bronze material (1) according to claim 1 , characterized in that the copper-based bronze material (1) contains a bronze material (1) which is subjected to a polishing (B) process to remove roughness on the surface of the copper-based bronze material (1) and to obtain a rigid surface.9- A copper-based bronze material (1) according to claim 1 , characterized in that it contains a bronze material (1) subjected to a process of refining (C) by removing oil, dirt and other contaminants from the surface of the copper-based bronze material (1).10- The invention relates to a method for applying a boronizing treatment to a copperbased bronze material (1), characterized in that it comprises the following process steps;- cleaning of dirt, rust, paint residues and undesirable substances from the surface of copper-based bronze material (1),- cleaning and drying the inside of the tank (3) prior to boron surface hardening,- adding boronizing powder (2) into the tank (3) after cleaning the inside of the said tank (3),- closing the cover of the said tank (3), ensuring insulation by covering the tank (3) cover with high temperature resistant insulation material,- To prevent oxygen from reaching the bronze material (1) and to prevent oxidation during the boronizing process, transporting of protective gas (4) into the tank (3) with external means of transportation,- placing the insulated tank (3) with boronizing powder (2) agents and bronze material (1) into the furnace (6),- closing the aforementioned furnace (6) door, setting the temperature rates at which the boronizing heat treatment will be performed on the control panel (9) and- taking out of the tank (3) cooled in the furnace (6) after the boronizing process, and taking out of the bronze material (1).11- The method according to claim 10, characterized in that it comprises the process steps of cleaning the inside of the tank (3) using sandpaper in the range of 240-800 mesh, washing with alcohol and drying with compressed air.12- The method according to claim 10, characterized in that it comprises the process steps of adding copper powder to the empty part of the tank (3) on top of the boronizing powder (2) to prevent oxygen leakage and oxidation during boronizing at high temperature.13- The method according to claim 10, characterized in that said shielding gas (4) contains inert gases having a mixture of pure argon, pure nitrogen, argon and nitrogen with hydrogen.14- The method according to claim 10, characterized in that it comprises the process steps of transporting the protective gas (4) into said tank (3) by means of a gas pipe (5) made of steel material.15- The method according to claim 10, characterized in that it comprises the process steps of ensuring the flow of protective gas (4) into the tank (3) from the beginning to the end of the process.16- The method according to claim 10, characterized in that it comprises the process steps of pouring boron agent into each region of the material and coating the surface of the material with boron agent up to 4 cm below the tank (6) cover.17- The method according to claim 10, characterized in that it comprises the process steps of thermal spray and selective laser melting applied by spraying or melting specific powders onto the surface of the material; a thermochemical diffusion process in which boron atoms diffuse (diffuse) onto the surface of the bronze component placed in the tank (3), which is a closed container filled with a boron-releasing powder package.

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