KR101488905B1 - Sodium titanate for welding material and method for preparing the same - Google Patents

Abstract

The present invention relates to sodium titanate for welding materials and a process for producing the same. The sodium titanate according to the present invention was confirmed to have an excellent moisture absorption rate by being produced by mixing a sodium oxide (Na ₂ O) source and a titanium oxide (TiO ₂ ) source in a high frequency induction furnace, melting and cooling. It is excellent in industrial application because it exhibits excellent characteristics in low hydrogen fluoride cored wire (FCW) welding material which can reduce the brittle fracture caused by hydrogen as much as possible.

Description

[0001] Sodium titanate for welding materials and methods for preparing the same [0002]

The present invention relates to sodium titanate for welding materials and a process for producing the same.

In order to improve the stability of welding arc and slag formation during welding work in welding materials, sodium titanate to be added is improved in the hygroscopicity, which is the most desirable requirement characteristic with its original application purpose.

In order to minimize the brittle fracture caused by hydrogen, mechanical devices used in marine structures and extreme areas as well as shipbuilding industry are maximizing demand of low hydrogen absorbing materials with low hygroscopicity.

Conventional methods for producing sodium titanate for a welding material include hydrothermal synthesis, sintering, arc electric furnace, and the like.

When sodium thiocyanate is produced by hydrothermal synthesis, sodium titanate is produced by firing at 650-750 ° C in order to remove OH groups after synthesis, filtration and drying by a special device such as autoclave, but the average particle size is small and the fibrous, columnar or whisker And thus it is not suitable for welding materials because of its poor hygroscopicity (JP-A No. 11-130433).

In addition, when sodium thiocyanate was prepared by firing, sodium titanate was synthesized at a temperature of 700-900 ° C with a titanium oxide source size of 325 μm or less. However, The filling property and fluidity are poor and the hygroscopicity is not particularly good (JP-A-2003-112922).

In addition, it is necessary to use graphite electrode and graphite powder as a power source because it is possible to make sodium titanate ingot by completely melting the raw materials by arc electric furnace method. Therefore, it is necessary to use the graphite electrode and the graphite powder as the power source so that carbon is permeated in the sodium titanate melt, The carbon content is exceeded, and therefore, there is a problem of the manufacturer having to re-fired at 550 ° C or higher after crushing in order to reduce the carbon content.

In addition, when sodium titanate is produced by induction furnace melting, it is necessary to use complex equipment such as reheating device, molten metal mixing device (bubbling device) and molten metal discharge interruption device by cooling equipment, It is difficult to handle the molten metal, and the cost is high, and it is difficult to control the temperature of the molten metal, so that it is difficult to produce preferable sodium titanate having excellent moisture absorption resistance.

Therefore, sodium titanate prepared by the conventional method can not meet the above-mentioned demand.

In order to solve such a problem, there is a demand for a manufacturing method that minimizes the moisture absorption of sodium titanate by optimizing the synthesis by complete melting of the raw materials and the crystal growth of sodium titanate by adjusting the temperature of the melt.

In order to solve the above problems, the inventors of the present invention have studied to prepare sodium titanate having excellent hygroscopicity, and have found that when a mixture of a titanium oxide (TiO ₂ ) source and a sodium oxide (Na ₂ O) source is mixed in a high frequency induction furnace It is possible to produce sodium titanate for a welding material excellent in moisture absorption resistance when sodium carbonate is produced, and the present invention has been completed.

Accordingly, the present invention aims to provide sodium titanate for welding materials and a method for producing the same.

The present invention provides sodium titanate for a welding material and a process for producing the same.

It has been confirmed that sodium titanate according to the present invention has an excellent moisture absorption rate and is excellent in a welding material for low hydrogen fluoride FCW (Flux Cored Wire) which has a low moisture absorptivity which can reduce the brittle fracture due to hydrogen, It has high value in industrial application by demonstrating its characteristics.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram showing an apparatus for producing sodium titanate. FIG.
FIG. 2 is a SEM photograph showing the sodium titanate of the present invention. FIG.
3 is a graph showing changes in moisture absorption rate with time for each sample.

The present invention

(a) blending a titanium oxide (TiO ₂ ) source and a sodium oxide (Na ₂ O) source at a weight ratio of 70 to 80: 20 to 30;

(b) melting the blended mixture in a high frequency induction furnace at 1200 to 1500 ° C; And

(c) cooling the melt in a lateral tilting process; The present invention also provides a method for producing sodium titanate for a welding material.

The present invention also provides sodium titanate for a welding material produced by the above-mentioned production method.

Hereinafter, the present invention will be described in detail.

The sodium titanate for welding material according to the present invention is characterized in that titanium dioxide and sodium oxide are mixed in a specific ratio and melted and cooled in a high frequency induction furnace.

The process for preparing sodium titanate according to the present invention will be described in detail as follows.

The step (a) is a step of blending raw materials for the production of sodium titanate, wherein a titanium oxide source and a sodium oxide source are mixed at a weight ratio of 70 to 80:20 to 30, and mixed with a mixer such as a ribbon mix, a cone mix or a vimix Lt; / RTI >

The titanium oxide source may be natural rutile or synthetic rutile, and the sodium oxide source may be sodium carbonate (Na ₂ CO ₃ ) or sodium hydroxide (NaOH) .

In the step (b), the compounded mixture is melted at 1200 ° C to 1500 ° C, preferably 1300 ° C to 1400 ° C using a high frequency induction furnace. When the temperature is lower than 1200 ° C., the degree of formation of sodium titanate is low, which is undesirable. When the temperature is higher than 1500 ° C., the particle size of sodium titanate formed becomes too large and volatile content in the melt is increased.

The high-frequency induction furnace is an electric furnace using a power source having a frequency equal to or higher than a commercial frequency, and is used to produce high-grade special steel. In the production of magnets, in particular, ALNICO-Mag is produced. Depending on the frequency of use, an intermediate frequency induction furnace and a high frequency induction furnace may be distinguished. The high-frequency induction furnace is also called a high-frequency electric furnace, and it is also used to make high-grade special steel (heat-resistant steel, high-speed steel, etc.). The object to be heated is placed in a dissolving chamber, and a current is passed through the object to be heated by induction of a high-frequency current flowing through the coil wound around the dissolving chamber to dissolve the object to be heated. Depending on the frequency used, the furnace up to 10 kHz can be distinguished as an intermediate frequency induction furnace and the furnace over 10 kHz as a high frequency induction furnace, beyond the commercial frequency. In the case of magnets, the temperature is raised to 1,710 ° C and induction heating is used at high frequencies to induce agitation, and after the metal has sufficiently melted, the casting begins to be poured into the mold. This is called casting.

The high-frequency induction furnace has a frequency of 400 to 2000 KHz and a power of 250 to 500 KW. The crucible is a combination of a copper tube and a stainless steel tube for water-cooling the inside of the crucible, .

The step (c) is a step of cooling the melt produced in the step (b), wherein the melt is cooled by a side tilting method.

The lateral tide cooling method is a method for instantaneous discharge of a melt, wherein the discharge line and the melter storage vessel are cooled to cool the sodium titanate melt in the bogie.

The production method of the present invention may further comprise, after the step (c), pulverizing sodium ticarbonate.

The crushing is carried out by using a crusher such as a jaw crusher, a pin mill, a roll break, a hammer mill and the like and has a suitable particle size of 0.1 to 0.3 mm as a welding material Crush it. In addition, it is preferable to lower the crushing strength at the time of crushing so that only the necking between the particles is broken without breaking the particles themselves.

The sodium titanate prepared by the above method is contained in a weight ratio of titanium oxide to sodium oxide of 5 to 6: 1, preferably in a weight ratio of 5.3 to 5.7: 1.

Sodium titanate having the above composition has excellent hygroscopicity when it is stored for 24 hours with a moisture absorption rate of 0.4% or less.

The sodium titanate produced by the method of the present invention exhibits a better moisture absorptivity than the sodium titanate sample prepared by the sintering method, the induction furnace melting method, or the arc furnace method, and thus can be usefully used for welding materials. Can be usefully used as a welding material for a low-hydrogen-based FCW (Flux Cored Wire) having a low moisture absorption rate which can reduce the brittle fracture caused by the brittle fracture.

Hereinafter, preferred embodiments of the present invention will be described in order to facilitate understanding of the present invention. However, the following examples are only for the purpose of easier understanding of the present invention, and the present invention is not limited by the examples.

Example 1 Preparation of sodium titanate by a high-frequency induction furnace process 1

Using the raw material titanium oxide (TiO ₂₎ as a source of natural rutile acid (Rutile) sodium carbonate in 95% and a sodium (Na ₂ O) circle oxide (Na ₂ CO ₃₎ in the ribbon 20 mixes were mixed at a weight ratio of 75: 25 Minute.

Then, after the temperature was raised from the high frequency induction furnace to 1300 ° C., the molten metal was instantaneously discharged through the melt discharge line, and then natural cooling was carried out in a molten metal storage crucible stored on the drum to produce sodium titanate Respectively.

The apparatus for producing sodium thiocyanate was shown in FIG. 1, and the shape of the sodium thiocyanate thus prepared was observed with an SEM. The result is shown in FIG.

As shown in Fig. 2, it was confirmed that the shape of the sodium titanate of the present invention indicates the particle type.

≪ Example 2 > Preparation of sodium titanate by a high frequency induction furnace process 2

Using the raw material titanium oxide (TiO ₂₎ as a source of natural rutile acid (Rutile) sodium carbonate in 95% and a sodium (Na ₂ O) circle oxide (Na ₂ CO ₃₎ in the ribbon 20 mixes were mixed at a weight ratio of 76:24 Minute. Then, after the temperature is raised to 1350 ° C in the high frequency induction furnace, the molten metal is instantaneously discharged through the melt discharge line, and natural cooling is carried out in a molten metal storage crucible stored on the truck to produce sodium titanate Respectively.

≪ Comparative Examples 1 to 3 > Preparation of sodium titanate with different production methods

Comparative Example 1. Preparation of sodium titanate by sintering

As a comparative example 1, sodium titanate was prepared by a method of producing sodium titanate by sintering.

Specifically, 95% of natural rutile and sodium carbonate (Na2CO3) as a source of sodium oxide (Na2O) were mixed as a raw material of titanium oxide (TiO2) at a weight ratio of 76:24. next. After 5 minutes of pulverization in a vibrating mill, 5% of distilled water was extruded as a binder to prepare a shaped body in a molding machine. The formed body was fired at 1000 캜 in a muffle furnace to prepare sodium titanate.

Comparative Example 2 Preparation of sodium titanate using an induction furnace

As Comparative Example 2, an induction furnace was used as in Examples 1 and 2, but the molten sodium titanate was discharged to the lower portion to prepare sodium titanate.

Comparative Example 3. Preparation of sodium titanate using an arc furnace

As Comparative Example 3, sodium titanate was melted in an arc furnace and reheated at a temperature of 550 DEG C or higher to prepare sodium titanate.

The components of sodium titanate prepared in Examples 1 and 2 and Comparative Examples 1 to 3 were analyzed and shown in Table 1.

division Chemical composition (%) TiO ₂ Na ₂ O SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ ZrO ₂ Cr ₂ O ₃ Equipment used Comparative Example 1 81.33 15.3 1.07 0.79 0.42 0.58 0.17 Calcining furnace Comparative Example 2 81.82 15.1 1.04 0.60 0.35 0.58 0.11 Guide rail lower Comparative Example 3 82.31 14.6 0.10 0.53 0.42 0.60 0.15 Acro Example 1 81.08 15.6 0.10 0.82 0.37 0.61 0.16 Guide rail side Example 2 81.37 15.2 1.1 0.66 0.50 0.63 0.15 Guide rail side

As shown in Table 1, it was confirmed that sodium titanate according to the present invention contained titanium oxide and sodium oxide in a weight ratio of 5 to 6: 1.

<Experimental Example 1> Measurement of hygroscopicity of sodium titanate

For the measurement of the moisture absorption rate of the sodium titanate prepared in Examples 1 to 2 and Comparative Examples 1 to 3, each sample was weighed by 20 g and stored in a container having an initial moisture content of 0.01 to 0.1% and a relative humidity of 80% And the moisture absorption amount was measured at each elapsed time. The results are shown in Table 2 and FIG.

division Absorption rate (%) with elapsed time 0 4 hours elapsed 8 hours elapsed 24 hours elapsed Comparative Example 1 0.05 1.09 1.23 1.19 Comparative Example 2 0.04 0.61 0.68 0.58 Comparative Example 3 0.06 0.31 0.36 0.32 Example 1 0.05 0.35 0.35 0.35 Example 2 0.06 0.33 0.32 0.31

As shown in Table 2 and FIG. 3, the sodium titanate prepared according to Example 1 and Example 2 retained the moisture absorption rate within 0.4% when stored in a container having a relative humidity of 80% for 24 hours, It has been confirmed that it has an excellent moisture absorption rate as compared with sodium titanate.

Claims (7)

(a) blending a titanium oxide (TiO ₂ ) source and a sodium oxide (Na ₂ O) source at a weight ratio of 70 to 80: 20 to 30;
(b) melting the mixture blended in the step (a) in a high frequency induction furnace at 1200 to 1500 ° C; And
(c) cooling the molten mixture in the step (b) by a side tilt method;
Wherein the method comprises the steps of: The method according to claim 1, wherein natural rutile or synthetic rutile is used as the titanium oxide (TiO ₂ ) source. The method for producing sodium titanate for welding material according to claim 1, wherein sodium carbonate (Na ₂ CO ₃ ) or sodium hydroxide (NaOH) is used as the sodium oxide (Na ₂ O) source. [3] The method of claim 1, wherein the high frequency induction furnace has a frequency of 400 to 2000 KHz and a power of 250 to 500 KW. The crucible is formed of a combination of copper and stainless steel pipes for water- And a cooling device is attached to the upper surface of the substrate. The method for producing sodium titanate for welding material according to claim 1, further comprising a step of grinding sodium titanate after the step (c). The method for producing sodium titanate for welding material according to claim 5, wherein the powder is pulverized so that the average particle diameter of sodium titanate is 0.1 to 0.3 mm. 6. A process for producing a semiconductor device according to any one of claims 1 to 6, wherein titanium oxide (TiO ₂ ) and sodium oxide (Na ₂ O) are contained in a weight ratio of 5 to 6: 1, Wherein the titanium nitride powder is a sodium titanate powder.

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