KR100711833B1 - Alloy target and method for manufacturing ti-al-si alloy target by mechanical alloying and spark plasma sintering - Google Patents

Abstract

The present invention relates to a target manufacturing process and a product thereof, and more particularly to a target manufacturing process for nano-structure coating for the development of a target for sputtering or arc ion plating used in high-speed processing tool and its product.

To this end, the raw material powder and balls are mixed at a predetermined ratio of charge ratio, and then mechanical alloying process is performed to uniformly distribute Ti, Al, and Si elements in the raw powder, and to finely granulate the grains in the powder to nano size. After the finely granulated raw material powder is added, the spark plasma sintering process is performed to uniformly distribute Ti, Al, and Si elements in the raw material powder, and to sinter the finely grained particles to nano size. Forming the to form a target.

According to the above configuration, through the mechanical alloying process and the spark plasma sintering process, the grains inside the raw material powder can be finely granulated to nano size, and the powder can be secured to a uniform size, and the Ti, Al, Si inside the raw material powder can be obtained. By uniformly distributing the alloying elements, the Ti-Al-Si alloy sintered body having excellent physical properties can be manufactured and used as a next-generation nanostructure coating material of a high speed processing tool.

Nano, target, mechanical alloying method, spark plasma sintering method, Ti-Al-Si alloy system.

Description

Alloy target and method for manufacturing Ti-Al-Si alloy target by Mechanical Alloying and Spark Plasma Sintering}

1 is a cross-sectional view schematically showing a coating system in which a sputtering process and an arc process are combined according to the prior art;

2 is a cross-sectional view showing the structure of a ball mill for a mechanical alloying process according to the present invention;

Figure 3 is a photograph showing the distribution of alloying elements in the powder subjected to the mechanical alloying process according to the present invention,

Figure 4 is a photograph showing the microstructure of the powder subjected to the mechanical alloying process according to the present invention,

5 is a schematic diagram showing an apparatus structure for a spark plasma sintering process according to the present invention;

Figure 6 is a photograph showing the microstructure of the sintered body manufactured by the spark plasma sintering process according to the present invention,

Figure 7 is a graph showing the degree of shrinkage of the sintered body during the spark plasma sintering process according to the present invention.

The present invention relates to a target manufacturing process and a product thereof, and more particularly to a target manufacturing process for nano-structure coating for the development of a target for sputtering or arc ion plating used in high-speed processing tool and its product.

In general, the sputtering method refers to the formation of a thin film on the surface of an substrate when atoms with energy collide with a target, and atoms or molecules come out of the target. The principle is that if the target is applied to the (-) pole and the substrate is the (+) pole, and a high voltage is applied in an Ar atmosphere of 1 to 2 Torr, the Ar gas near the (-) pole is ionized and becomes Ar ⁺ , Crash. Molecules or atoms protruding by the ion bombardment are attached to the substrate of the (+) electrode to form a thin film.

Arc ion plating is a method of forming a thin film by a similar principle, and activates the target material in the arc region, not the plasma region. As such, the surface of the substrate material on which the thin film is formed by sputtering or arc ion plating from the target material has a decorative color such as gold or silver, and has characteristics such as corrosion resistance and wear resistance through high hardness and excellent physical properties.

On the other hand, in recent years in various manufacturing industries, including automobiles, shipbuilding, electronics, high speed and high efficiency of the cutting process is urgently required. The key to this demand lies in high-speed processing technology, which enhances the company's competitiveness as productivity increases.

In order to cope with this, a cutting tool for high-speed machining is a trend to introduce a high-performance coating film having excellent durability and corrosion resistance.

In particular, as an example by high-speed processing, high heat (700 ~ 800 ℃) occurs, it is characterized by a high feed rate. The characteristics of the high-performance coating film must be able to withstand the high temperatures generated during high-speed processing (excellent oxidation resistance), avoid the precise chip tip phenomenon common in high-speed processing (good toughness), and improve the wear resistance (excellent hardness). Coating film development is essential.

TiAlN is preferred as an optimal coating layer for improving the lifespan of such a high speed machining tool. In particular, in recent years, research has been conducted to maximize the characteristics by nanoning the microstructure of TiAlN. The above-mentioned, important in forming the nanostructured coating film is to make the crystallization of the crystal grains and the thermally unstable nanostructures stable. To this end, in the developed countries, studies are being made to improve thermal stability by effectively dispersing the precipitated phase by adding B, Si, Cr, etc. to TiAlN.

As the sputter target used until recently to form a coating layer having the above characteristics, as shown in FIG. 1, a process using a SiAl or Cr target in combination with a target composed of a TiAl alloy was used.

However, the above-described conventional target manufacturing process has a problem in that the determination of the optimal process for nanostructure coating is complicated because two or more types of targets are installed in the chamber.

That is, when sputtering is performed using a target manufactured by the conventional target manufacturing process as described above, coating must be performed by separately installing the TiAl target and the Si target in the sputtering and arc coating systems of the complicated shape as shown in FIG. 1. There is a difficulty.

As a result, the sputtering process and the arc process have to be determined separately, the atmosphere has to be set according to the two processes, and the difficulty of changing the process parameters according to the amount of coating material from each comes with the difficulty.

On the other hand, in Korea, high-quality target materials are imported from foreign countries. The characteristics of the target are that the alloy components must be uniformly dispersed, and high purity and density, smaller grain size and uniform size distribution, uniform microstructure and This is because a variety of conditions are required to improve the properties of the final product, such as composition distribution.

Powder metallurgy is the best method to satisfy the above conditions. In the case of Ti-Al alloy system, the closer to Al system, the smaller the Ti solid solubility in Al and the longer the cooling period. There is a problem that is difficult to obtain.

In particular, since Al ₃ Ti is composed of alloying elements, it is difficult to make an accurate alloy even by a quenching method. Also, when Si is included in the alloy system, the alloy composition is more complicated, so that the general casting method is uniform. There is also a problem in that the manufacture of the resin becomes impossible.

The present invention has been made to solve the conventional problems as described above, through the mechanical alloying process and the spark plasma sintering process can produce a Ti-Al-Si alloy-based target having fine grain, uniform and excellent physical properties. The present invention provides a method for producing a target for nanostructure coating and a product thereof.

In the method for manufacturing a target for nanostructure coating of the present invention for achieving the above object, in the target manufacturing process used for sputtering for improving the life of a high-speed processing tool, the raw material powder and a ball of a predetermined size are charged at a predetermined ratio. Performing a mechanical alloying process after mixing in a ratio to uniformly distribute Ti, Al, and Si elements in the raw material powder and at the same time finely granulate the grains in the powder to nano size; After inputting the raw material powder after the fine granulation step, the spark plasma sintering process is performed to uniformly distribute Ti, Al, and Si elements in the raw material powder, and at the same time, finely granulate the crystal grains in the powder to nano size. It characterized by comprising a step of forming a sintered body of.

In addition, the target for nano-structure coating of the present invention is a target used for sputtering to improve the life of a high-speed processing tool, the raw material powder and a predetermined size of the ball by mixing a predetermined ratio of charge ratio and then performing a mechanical alloying process While uniformly distributing Ti, Al, and Si elements in the powder, and finely granulating the crystal grains in the powder to nano size, injecting the finely granulated raw powder, and performing a spark plasma sintering process, It is characterized in that it is produced by uniformly distributing the elements of Ti, Al, Si, and forming a sintered body in a state in which the grains inside the powder are finely granulated to a nano size.

When described in detail with reference to the accompanying drawings a preferred embodiment of the present invention.

2 to 7 are directed to a method for producing a target for nano-structure coating and the product of the present invention, first, the method for producing a target for nano-structure coating is composed of a nano-particle granulation step and a sintered body forming step.

In other words, in the nano-particulation step, the raw material powder and the ball having a predetermined size are mixed at a predetermined ratio of charge ratio, and then a mechanical alloying process is performed to uniformly distribute Ti, Al, and Si elements in the raw material powder and simultaneously crystal grains in the powder Is finely granulated to nano size.

Here, the mechanical alloying process (Mechanical Alloying (MA)) described above is briefly described, in which a powdered specimen is put together with a ball into a container of a certain size and alloyed by a mechanical force. All the reactions are performed, which makes it possible to alloy even between alloying compositions that are difficult to alloy, and is an optimal process for dispersing oxides and carbides with little solid solution.

In addition, it is possible to refine the grains by sufficient energy therein to produce a powder having a grain size of less than nanometers.

Referring to the nano-particle granulation step through the mechanical alloying process as described above in more detail with reference to Figure 2, after mixing the ball powder in a ratio of 1:50 ~ 1: 100 by weight of the raw material powder and the ball, the ball mill nitrogen B. It is maintained in a hydrogen atmosphere and driven to rotate for 10-100 hours at a speed of 200-300 rpm.

At this time, the size of the ball is to use the 3 / 16inch ~ 6 / 16inch, the reason is that when the size of the ball is 2/16 inch or less, it is not possible to supply enough energy to the inside of the ball mill grain refinement effect inside the raw material powder This is because when the size of the ball is reduced to 7/16 inch or more, the amount of the ball is small compared to the weight, and the size of the ball has a great influence on the particle size reduction.

Subsequently, in the sintered body forming step, the raw material powder subjected to the nano-granulation step is added, and then a spark plasma sintering process is performed to uniformly distribute Ti, Al, and Si elements in the raw material powder, and to simultaneously crystallize the grains in the powder. The fine sintered compact is formed.

Here, the above-described spark plasma sintering process (Spark Plasma Sintering, SPS) will be described briefly. By applying an electric current to a powder placed under a constant pressure to generate a plasma between the powder particles, the surface is activated and lowered. This is a method of rapidly sintering a powder at a temperature.

The spark plasma sintering process is easy to sinter high-temperature materials or oxides that are difficult to sinter by strong powder surface activation due to plasma generation, and also enables rapid sintering at low temperatures. The structure is maintained and sintered.

When the sintered body forming step through the spark plasma sintering process as described above is described in more detail with reference to FIG. 5, the raw material powder granulated according to the size of the sintered body to be manufactured is put between the jig and the sintering pressure is applied at the same time. By applying a DC pulse current of the current density to generate a plasma between the raw material powder and to activate the surface to produce a sintered body.

On the other hand, the target produced by the method for producing a target for nanostructure coating, the mechanical alloying process and the spark plasma sintering process is sequentially performed to uniformly distribute Ti, Al, Si elements in the raw material powder, powder The sintered compact (target) is manufactured in the state which the internal crystal grain was made into the microparticles | fine-particles.

At this time, the grain size inside the raw material powder is formed to less than 20nm both after the mechanical alloying process and after the spark plasma sintering process as shown in Figure 4 and 6, the size of the raw material powder is uniformly formed to less than 10㎛ do.

Here, the weight ratio of Ti, Al, and Si elements of the sintered compact is composed of Ti: 47 to 10 wt%, Al: 50 to 80 wt%, and Si: 3 to 10 wt%.

Referring to the operation and effect of the present invention configured as described in detail as follows.

In order to manufacture the target through the method for manufacturing a target for nanostructure coating of the present invention, first, the raw powder and the ball are mixed in a ratio of 1:50 in the ball mill as shown in FIG. 2, and then rotated at a speed of 200 rpm for 20 hours or more. Let's do it.

Figure 3 is a SEM photograph showing the distribution of alloy elements in the raw material powder through the rotational drive as described above, Ti, Al, Si alloy elements that were not uniform until the milling process 5 hours evenly distributed within the powder after 20 hours You can see that.

In addition, the structure of the powder produced after 20 hours has a size of less than 20nm as shown in Figure 4, it can be seen that the powder size also shows a constant spherical shape with a size of 10㎛.

Therefore, through the above mechanical alloying process, Ti, Al, Si alloy elements can be uniformly distributed in the raw material powder, and the grain size in the powder can be finely granulated to a nano size of less than 20 nm, and the powder itself The size can also be secured at a constant 10㎛.

As such, after the nanostructured powder is produced, the step of molding the powder is generally performed at a temperature that is two thirds of the melting point of the alloy.

However, when forming through the above method, the forming temperature of the Ti-Al-Si alloy system is raised to 1000 ℃ or more, when the sintering is performed under such a high temperature and a constant pressure, the nanostructure in a metastable state Disappears due to grain growth. In addition, when sintering a large molded body in the horizontal direction under one-way pressure, such as hot pressing (Hot Pressing), it is difficult to obtain a uniform density in the specimen due to the uneven distribution of pressure.

Therefore, Hot Isostatic Pressing is widely used to make the pressure isotropic. Furthermore, the powder is sintered by using the spark plasma sintering process, which is a representative sintering method that can minimize the sintering time or lower the sintering temperature. .

In order to sinter the powder, as shown in FIG. 5, the optimum amount of powder required for the sintered compact of a desired size is put between the jig and a DC pulse current of high current density is applied under pressure. Therefore, plasma is generated between the powders to activate the surface, so that the powder can be sintered in a short time.

6 is a photograph showing the microstructure of the sintered body sintered through the above process, the grain size inside the powder is finely granulated to a nano size of less than 20nm, and the size of the powder itself is constantly secured to 10㎛, In particular, it can be seen that the Ti, Al, Si alloy elements are uniformly distributed in the raw material powder.

At this time, the sintered body sintered as described above is to generate a plasma to observe the shrinkage of the sintered body during sintering while raising the temperature and determine the point where no further shrinkage is observed as the optimum sintering point.

The reason is that after the sintering shrinkage no longer occurs, the continuous generation of plasma causes the alloy powder due to excessive heat to be liquefied, resulting in higher unevenness of the structure. Therefore, when the shrinkage of the sintered compact is no longer observed, a sintered compact having an optimum sintered density of 99% or more can be obtained as shown in the graph of FIG.

On the other hand, the present invention has been described in detail only with respect to the specific examples described above it will be apparent to those skilled in the art that various modifications and variations are possible within the technical scope of the present invention, it is natural that such variations and modifications belong to the appended claims. .

As described above, the present invention can finely granulate the grains in the raw material powder to nano size through the mechanical alloying process and the spark plasma sintering process, and ensure the powder in a uniform size, in particular, Ti, Al in the raw material powder. The Si alloy element can be uniformly distributed. Therefore, the Ti-Al-Si alloy sintered body having excellent physical properties can be manufactured and used as a next-generation nanostructure coating material of a high speed processing tool.

Moreover, instead of installing and coating the TiAl target and the Si target separately as in the prior art, Si is uniformly distributed in the TiAl alloy to form a nanocomposite structure with one target, thereby simplifying and simplifying a series of processes required for manufacturing. There are also effects that can be made.

Claims (8)

delete In order to be used for the sputtering to improve the service life of the high speed processing tool, the raw material powder and the ball are mixed at a charging ratio, and then a mechanical alloying process is performed to uniformly distribute a plurality of elements inside the raw material powder, Finely granulating the grains, and inputting the raw material powder subjected to the fine granulating step, and then performing a spark plasma sintering process to uniformly distribute the plurality of elements in the raw material powder and simultaneously to form the crystal grains in the powder. In the target manufacturing process including the step of forming a sintered compact in a fine granulated state, In the granulation step, In order to uniformly distribute Ti, Al, and Si elements in the raw powder, and to finely grain the grains in the powder, the raw powder and the ball are mixed in a ball mill at a ratio of 1:50 to 1: 100 by weight. After, the ball mill is maintained in a nitrogen or hydrogen atmosphere to drive the nano-structure coating target manufacturing process, characterized in that for 10 to 100 hours rotational drive at a speed of 200 ~ 300rpm. According to claim 2, The size of the ball nano-structure coating target manufacturing process, characterized in that using the 3/16 inch ~ 6/16 inch. delete delete delete In order to be used for the sputtering to improve the service life of the high speed processing tool, the raw material powder and the ball are mixed at a charging ratio, and then a mechanical alloying process is performed to uniformly distribute a plurality of elements inside the raw material powder, After finely granulating the grains, and inputting the finely granulated raw powder, a spark plasma sintering process was performed to uniformly distribute the plurality of elements in the raw powder and at the same time to finely grain the crystal grains in the powder. In the target formed by forming the sintered compact of the state, After the mechanical alloying process, Ti, Al, and Si elements are uniformly distributed in the raw powder, but the raw powder is formed to have a size of less than 10 μm, and the grain size of the raw powder is formed to a nano size of less than 20 nm. ; After the spark plasma sintering process, Ti, Al, Si elements are uniformly distributed in the raw material powder, but the raw powder is formed in a size less than 10 μm, and the grain size in the raw material powder is formed in a nano size of less than 20 nm. Target for nano-structure coating, characterized in that. According to claim 7, wherein the weight ratio of Ti, Al, Si elements in the sintered compact is characterized in that the composition of Ti: 47 ~ 10wt%, Al: 50 ~ 80wt%, Si: 3 ~ 10wt% Targets for structural coatings.

Images