JP3162288B2 - Particle ejection nozzle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a sand blast,
The present invention relates to a particle ejection nozzle used for shot blasting, shot peening, and the like, and more particularly, to a particle ejection nozzle at least part of which is formed of a ceramic sintered body.

[0002]

2. Description of the Related Art For example, in a sandblast nozzle as a particle ejection nozzle as described above, since particles such as abrasive grains pass through the inner surface while colliding at a high speed, particles such as crystal grains constituting the nozzle are worn away. There is a problem of causing wear by dropping or falling off. In particular, iron nozzles, which have been most commonly used, have a drawback that wear is apt to progress and the nozzle life is short in a short time. Therefore, in place of iron, alumina sandblast nozzles having excellent wear resistance have been widely used in recent years.

[0003]

The durability of the alumina sand blast nozzle is superior to that of the iron sand blast nozzle. However, in order to further reduce the time and effort of nozzle maintenance and to urge the automation or labor saving of the processing, There is a strong demand for the development of a nozzle having a longer life than that of the nozzle.

An object of the present invention is to provide a particle ejection nozzle which is more durable than a conventional alumina nozzle.

[0005]

Means for Solving the Problems and Functions / Effects In order to solve the above-mentioned problems, a particle ejection nozzle of the present invention (hereinafter, referred to as “particle ejection nozzle”)
At least a part thereof is made of the following ceramic material. That is, the material is a sintered body having a structure in which ceramic particles containing at least one of ZrO ₂ and HfO ₂ as a main component are dispersed in a ceramic matrix containing Al ₂ O ₃ as a main component. Of the particles, a portion corresponding to 3% by weight or more of the sintered body is a tetragonal phase.

The inventors of the present application have found that a ceramic material that satisfies the above conditions exhibits excellent abrasion resistance characteristics, and when applied to a particle ejection nozzle used for sand blasting, shot blasting, shot peening, or the like, the life thereof is reduced. They have found that they can improve significantly.

The reason that the above ceramic material exhibits excellent wear resistance is presumed as follows. That is, it is known that ZrO ₂ and HfO ₂ , which are the main components of the ceramic particles, undergo transformation between three types of phases having different crystal structures with a change in temperature. Low temperature side, monoclinic phase, higher temperature side, tetragonal phase,
Further, it becomes a cubic phase on the high temperature side. Therefore, when considering a sintered body containing the above-mentioned ceramic particles, if the whole of the ceramic particles is made of at least one of ZrO ₂ and HfO ₂ , almost all of them near room temperature. It is considered to be a monoclinic phase. However, as a stabilizing component for ZrO ₂ and HfO ₂ ,
By dissolving a certain amount or more of an alkaline earth metal oxide or a rare earth metal oxide (for example, calcia (CaO) or yttria (Y ₂ O ₃ )), a monoclinic phase and a tetragonal phase are formed. Is known to be able to stabilize the tetragonal phase in a temperature range near room temperature.

Here, it is known that the above-mentioned phase transformation from a tetragonal phase to a monoclinic phase is based on a so-called martensitic transformation mechanism or a similar phase transformation mechanism. When stress is applied, the transformation temperature rises and the tetragonal phase undergoes stress-induced transformation to the monoclinic phase, and the strain energy due to the stress is consumed as a driving force for the transformation, resulting in the added The stress will be relieved. Therefore, in a ceramic material in which ceramic particles containing a tetragonal phase are dispersed, when the sandblast abrasive grains collide and cracks or the like are generated, the ceramic particles are present near the crack tip. In this case, the tetragonal phase is transformed into a monoclinic phase by the stress concentrated at the crack tip. Thereby, it is considered that the stress concentration on the tip of the crack is alleviated, the propagation of the crack is prevented or alleviated, and the wear resistance of the material and the nozzle is improved. In addition, when a tetragonal phase is transformed into a monoclinic phase, volume expansion accompanies, and this causes a compressive stress on the material surface. It is presumed that this is one of the factors that makes it difficult to occur.

When the amount of the tetragonal phase contained in the ceramic particles is less than 3% by weight of the sintered body, the above-mentioned stress-induced phase transformation is unlikely to occur, and the wear resistance of the material is sufficiently ensured. become unable. The amount of the tetragonal phase is preferably at least 10% by weight of the sintered body, more preferably at least 20% by weight. On the other hand, when the content of the tetragonal phase is 3 wt.
In the range of 50% by weight, the wear resistance of the material gradually increases, but when it exceeds 50% by weight, it hardly changes. Therefore, when the total content of the tetragonal system phase exceeds 50% by weight, the wear resistance is not improved, and the content of ZrO ₂ or HfO _{2 which} is more expensive than Al ₂ O ₃ is increased. This results in only an increase in material cost. Therefore, the amount of the tetragonal phase is desirably 50% by weight or less, more desirably 40% by weight or less, and further desirably 30% by weight or less.

[0010] The ceramic particles have a total content of at least one of an alkaline earth metal oxide and a rare earth metal oxide as a stabilizing component of the tetragonal phase, which is 1 to the total amount of the ceramic particles. It is desirable to contain 0.5 to 8 mol%. When the content of the stabilizing component is 1.
When the content is less than 5 mol%, the content of the monoclinic phase is increased, and as a result, the content of the tetragonal phase is relatively reduced, and the above-mentioned stress relaxation effect cannot be sufficiently obtained. This causes insufficient wear. On the other hand, when the content of the stabilizing component exceeds 8 mol%, the content ratio of the cubic phase increases, and similarly, the wear resistance of the material becomes insufficient. The content of the stabilizing component is more desirably 1.5 to 5 mol%, and further desirably 2 to 4 mol%.

Incidentally, as a stabilizing component of the tetragonal phase, specifically, Y ₂ O ₃ has a higher strength of the obtained ceramic material as compared with the case where other stabilizing components are used. Since they are relatively inexpensive, they are suitably used in the present invention. On the other hand, CaO and MgO are not as strong as those using Y ₂ O ₃ , but the strength of the obtained ceramic material is relatively high, and it is even cheaper than Y ₂ O ₃ .
Similarly, it is suitably used in the present invention. Note that Y ₂ O ₃ , Ca
O and MgO may be used alone or in combination of two or more.

Next, Z, which is the main component of the ceramic particles,
Since rO ₂ and HfO ₂ are similar in chemical and physical properties, either one of them can be used alone, or both can be used in combination. However,
Since ZrO ₂ is less expensive than HfO ₂ , it can be said that it is more desirable that the ceramic particles be composed mainly of ZrO ₂ . Incidentally, a generally supplied ZrO ₂ raw material of normal purity often contains a trace amount of HfO ₂ , but when such a raw material is used, the contained HfO ₂ is reduced for the above-mentioned reason. There is little need for active removal.

The ceramic particles have a ratio CW between the cubic phase existing weight CW and the tetragonal phase existing weight TW.
/ TW is preferably less than 1. The cubic phase is
When the content of the above-mentioned stabilizing component is increased and the transformation point with the tetragonal phase is lowered, or when the firing temperature is 1600
When the temperature exceeds ℃, it is easily formed, and has a property that crystal grains are likely to be coarsened during firing as compared with a monoclinic phase or a tetragonal phase. Then, the crystal grains of the cubic phase that are coarsened have a low interfacial bonding force with other crystal grains, so that they are easy to drop, and when the amount of the cubic phase increases until the above ratio exceeds 1, The formation amount of such coarse crystal grains also increases, which leads to impairment of the wear resistance of the material. Therefore, the ratio CW / TW should be less than 1, preferably less than 0.5, more preferably less than 0.5.
It is better to be less than 1.

Next, the particle ejection nozzle has an inlet and an ejection outlet for an airflow containing particles to be ejected, and an airflow passage for guiding the airflow from the inlet to the ejection outlet.
At least a portion including the inner surface of the airflow passage can be made of the ceramic material. That is, since the portion including the inner surface of the airflow passage is made of the above-described material, the durability of the nozzle can be significantly improved.

The portion of the nozzle formed of the ceramic material can be manufactured as follows.
That is, ZrO ₂ , HfO ₂ or a mixture thereof contains a predetermined amount of a stabilizing component to form a powder, and this is mixed and dispersed in alumina powder to obtain a raw material powder. It is molded into a predetermined shape by molding or the like and sintered. The average particle size of the raw material powder is 0.1 to
It is desirable to set it in the range of about 1.5 μm. If the average particle size exceeds 1.5 μm, the durability of the nozzle becomes insufficient. On the other hand, when the thickness is less than 0.1 μm, it takes a long time to grind the raw material, which causes a rise in raw material cost. The average particle size is more desirably set to 0.2 to 0.8 μm. On the other hand, the sintering temperature is desirably set in the range of 1500 to 1650 ° C. When the sintering temperature exceeds 1650 ° C., the content ratio of the cubic phase becomes large, which causes the wear resistance of the material to be insufficient. On the other hand, the sintering temperature is 1500 ° C
If it is less than sintering, sintering becomes insufficient, leading to insufficient strength. The sintering temperature is more preferably from 1520 to 16
The temperature is preferably set at 20 ° C.

[0016]

Embodiments of the present invention will be described below with reference to examples. ZrO ₂ raw material powder (average particle size 0.1 μm) and Al ₂ O _{3 having the} compositions shown in Tables 1 and 2
A raw material powder (average particle size: 0.5 μm) was blended, and wet mixing was performed using distilled water as a dispersion medium. After 6% by weight of a binder was added to this mixture with respect to the raw material powder, a dry raw material was obtained by a spray drying method. This base material is formed by a rubber press, processed into a nozzle shape, and further sintered at 1520 to 1750 ° C. for 1.5 hours. Each book was produced.

FIG. 1 shows the shape and dimensions (unit) of a sintered body (sand blast nozzle; hereinafter simply referred to as a nozzle) 1.
mm). That is, the nozzle 1 is formed in a substantially cylindrical shape that is long in the axial direction and has a gently tapered outer peripheral surface, and has an airflow inlet 2 at one end surface and a jet outlet 3 at the other end surface. A venturi pipe-shaped airflow passage 4 is formed along the axial direction of the nozzle 1 from the inlet 2 to the jet outlet 3 so as to pass through the center of the cross section of the nozzle 1. Note that the ZrO ₂ raw material powder has Y ₂ as a stabilizing component.
Those containing O ₃ in various ranges were used. In addition, Y ₂ O
The content of ₃ is such that the content ratio of the Y ₂ O ₃ component is in the range of 1.5 to 8 mol% with respect to the total amount of the ZrO ₂ component and the Y ₂ O ₃ component in the obtained sintered body. It was adjusted to become.

Three of the nozzles thus obtained were attached to the nozzle of a sand blast tester,
Was sprayed from the jet outlet 3 for 15 minutes at a jet pressure of 3.5 kg / cm ² . Then, the wear volume is determined by dividing the weight change amount of the nozzle before and after the test by the density of the nozzle (sintered body), and the wear volume is further divided by the usage amount of the used GC abrasive grains to obtain the corrected wear amount. I asked. As a comparative example, a similar test was performed on a commercially available alumina nozzle of the same type.

Next, the remaining three nozzle sintered bodies were attached to the nozzle portion of a sand blast tester, and GC
After the abrasive particles were sprayed, the time required for the initial inner diameter set to φ2.4 mm to expand to φ4 mm was measured, and this was defined as the life of the sandblast nozzle. Similarly, a test using a nozzle made of alumina was performed as a comparative example.

Next, a part of the nozzle sintered body is mirror-polished, and X-ray is polished on the polished surface by a diffractometer method.
Line diffraction was performed. In this case, in the obtained diffraction pattern, the main diffraction peaks (11 1) intensity peak positions appear close to each other with respect to the tetragonal phase and the cubic phase. From the ratio of the total intensity Im of (11 1) and (11-1) of the phase and the sum of the (11 1) intensity of the tetragonal phase and the cubic phase It + Ic, the monoclinic phase The abundance was determined. Next, the sintered body was mechanically pulverized and subjected to X-ray diffraction again to determine the (111) intensities I ′m and I′c of the monoclinic phase and the cubic phase. In this case, it is considered that almost all of the tetragonal phase of the sintered body is transformed into a monoclinic phase due to the mechanical stress caused by the pulverization. Therefore, the cubic phase is calculated from I′c / (I ′m + I′c) The phase abundance can be determined. The composition of each nozzle sintered body is I
It analyzed by CP (Inductively Coupled Plasma) spectroscopy. The above results are shown in Tables 1 and 2. In the compositions shown in the table, ZrO ₂ + Y ₂ O ₃ represents the ZrO ₂ component and Yr
_It shows the analysis value of the total amount with the ₂ O ₃ component.

[0021]

[Table 1]

[0022]

[Table 2]

That is, when the sand blast nozzle is manufactured from a material satisfying the conditions of the present invention, it can be seen that the life thereof is at most three times superior to that of the alumina sand blast nozzle.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a sandblast nozzle as a particle ejection nozzle of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sand blast nozzle 2 Inlet 3 Injection outlet 4 Air flow path

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B24C 5/04

Claims (6)

(57) [Claims] 1. A sintered body having a structure in which a ceramic particle mainly containing at least one of ZrO ₂ and HfO ₂ is dispersed in a ceramic matrix mainly containing Al ₂ O ₃ , A particle ejection nozzle characterized in that at least a part of the body is made of a ceramic material in which a portion corresponding to 3% by weight or more of the sintered body is a tetragonal phase. 2. The particle ejection nozzle according to claim 1, wherein the ceramic material has a tetragonal phase in a portion corresponding to 50% by weight or less of the sintered body in the ceramic particle body. 3. The ceramic particles according to claim 1, wherein a total of at least one of an alkaline earth metal oxide and a rare earth metal oxide as a stabilizing component of the tetragonal phase is based on the total amount of the ceramic particles. 1.5 to
The particle ejection nozzle according to claim 1, which contains 8 mol%. 4. The ceramic particle body contains ZrO ₂ as a main component and Y ₂ O ₃ , as a stabilizing component of the tetragonal phase.
The particle ejection nozzle according to claim 3, wherein the particle ejection nozzle contains at least one selected from CaO and MgO. 5. The ceramic particle body according to claim 1, wherein a ratio CW / TW of an existing weight CW of the cubic phase to an existing weight TW of the tetragonal phase is less than 1. Particle ejection nozzle. 6. An inlet and an outlet for an airflow containing particles to be ejected, and an airflow passage for guiding the airflow from the inlet to the outlet, wherein at least a portion including the inner surface of the airflow passage is made of the ceramic material. The particle ejection nozzle according to any one of claims 1 to 5, wherein