JPH0763950A - Optical fiber connector parts made of zirconia - Google Patents

Abstract

PURPOSE:To provide an optical fiber connector part having excellent heat resistance and good workability by using a component compsn. mainly consisting of zirconia contg. cerium oxide as a stabilizing agent as the ceramics to be used for ferrules and split sleeves as the optical connector parts. CONSTITUTION:The ferrule 3 having a fine hole for inserting and holding an optical fiber among the connectors for connecting the optical fibers and the sleeve 4 for connecting and holding this ferrule are form of out of the zirconia ceramics mainly consisting of the cerium oxide as the stabilizing agent. The cerium oxide zirconia ceramics is higher in fracture toughness than the zirconia formed by using other stabilizing agents and exhibits plastic deformation in a limited compsn. region. Further, particles are hardly dislodged when sintered compacts are worked. In addition, workability is good. Since the thermal stability of this ceramics is extremely good, the reliability as the material is excellent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical connector part made of zirconia having excellent heat deterioration characteristics and high strength and toughness. The ferrule and split sleeve are used for optical connectors for multimode optical fibers, single mode optical fibers, etc., and are particularly suitable for connecting optical fibers that require high dimensional accuracy. More specifically, in an optical fiber communication system, which is expected to grow rapidly as a communication medium in the future, when manufacturing a ferrule as a joining part of a connector used for fiber connection, and a sleeve for fixing the ferrules together with ceramics, By using zirconia partially stabilized mainly by cerium oxide as the ceramics, it is possible to prevent an increase in axial misalignment between optical fibers, which leads to a decrease in dimensional accuracy due to particle loss, and thus an increase in splice loss, and for a long time in any environment. The present invention relates to a ceramic material that can be used without deterioration.

[0002]

2. Description of the Related Art Conventionally, a connector used for optical fiber communication is composed of a plug 2 and an adapter 1 as shown in FIG. As shown in FIG. 2, a ferrule 3 having a very finely processed fine hole 31 in the center is housed in the plug 2 as shown in FIG. 2, and an optical fiber is inserted therethrough. And integrate it with the ferrule. The tip of this ferrule is spherically processed, and the pair of plugs 2 are crimped and connected in the adapter 1 from the left and right. At this time, if there is an axis shift in the connection between the optical fiber terminals, optical loss occurs, and as a result, a large transmission loss occurs. Therefore, the ferrule part is required to have extremely high accuracy in terms of outer diameter, inner diameter, length and the like.

Currently, ferrule materials are made of resins, metals, ceramics, etc., but ceramics have the characteristics of high hardness and a small coefficient of thermal expansion as compared with resins and metals, and in particular, alumina, zirconia, etc. Since ceramics have a very small grain size of the sintered body, the precision when processed is good.

A split sleeve 4 as shown in FIG. 3 is housed in the adapter 1 to elastically hold and align the two ferrules 3. Phosphor bronze is usually used as the split sleeve material, but split sleeves made of zirconia have also been developed in recent years.

As for zirconia, most of the partially stabilized zirconia added with yttrium oxide is used. Since this material has a small grain size and good workability, the surface accuracy of the product is very good, and since the toughness is high, defects such as chipping are hard to occur, and high strength
It has extremely excellent characteristics. On the other hand, however, this material has the drawback of poor heat resistance. 100 ~
At a temperature of 300 ° C., in particular, when it contains water vapor, the transition from the tetragonal system to the monoclinic system is likely to occur, the surface layer is deteriorated, and the product is deformed due to the volume expansion at this time, The particles may fall off, which may lead to poor connection when reused. Heat resistance is an essential condition for guaranteeing the reliability required for communication equipment.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical fiber connector part using a zirconia ceramic material having excellent heat resistance and good workability.

[0007]

Means for Solving the Problems In order to solve the above problems, the present inventors have studied zirconia materials, and as a result, if the materials are set centering on zirconia partially stabilized with cerium oxide, It has been found that the heat resistance and hot water resistance are excellent and the machinability is improved, and the present invention has been completed.

[0008]

[Function] In the case of yttrium oxide-based zirconia,
It is often used as a so-called partially stabilized zirconia containing 2 to 4 mol% of yttrium oxide. This material has many excellent properties such as high bending strength, high fracture toughness, and good processing surface accuracy because of its small grain size, but it has the drawback of being weak against heat. In order to improve the heat resistance, yttrium oxide should be added in an amount of 6 to 10 mol% to completely stabilize it, but in this case, the strength and toughness are greatly reduced, and the function as a structural material is almost lost. Will end up.

Further, both calcium oxide and magnesium oxide have the problems of weak strength and large particle size.

On the other hand, it is known that cerium oxide-based zirconia ceramics have higher fracture toughness than zirconia using other stabilizers and show plastic deformation in a limited composition region. Therefore, when the sintered body is processed, the particles are unlikely to fall off, and the workability is also good. In addition, the thermal stability is also very good, and therefore the reliability as a material is the best.

Therefore, it is preferable that the ceramics used for the ferrule and the split sleeve as the optical connector parts are basically zirconia mainly containing cerium oxide as a stabilizer.

The composition of cerium oxide is 3 to 30% by weight, preferably 12 to 20% by weight, and particularly 1
A high toughness value is obtained at around 6% by weight. It is also effective to add aluminum oxide in order to improve that the strength is slightly low. As a result, the preferable composition of the components is zirconium oxide 50 to 90% by weight, cerium oxide 3 to 30% by weight, yttrium oxide 0 to 8% by weight, and aluminum oxide 0 to 50% by weight. The presence of calcium, magnesium oxide, lanthanum oxide, etc. further improves the characteristics. The crystal phase of zirconia is mainly tetragonal, and besides this, cubic and monoclinic. Specifically, tetragonal crystal; 50 to 100%, cubic crystal; 0
50%, monoclinic; the ratio is 0 to 30%, but it is most effective when monoclinic is 10% or less and tetragonal is 70% or more.

FIG. 4 shows the Vickers indentations when a load of 20 kg is applied. Compared with the yttrium oxide type, the cerium oxide type has almost no cracks from the edges. This shows that the material has high toughness.

Next, FIG. 5 shows a surface layer of a cerium oxide (hereinafter referred to as Ce) zirconia sintered body and a yttrium oxide (hereinafter referred to as 3Y) zirconia sintered body under a saturated steam pressure of 170 ° C. 3 shows the change with time of the phase transition rate from tetragonal to monoclinic in. This shows that Ce-based zirconia is very excellent in thermal stability.

The effect is remarkable when the average particle size of zirconia is 10 μm or less, preferably 3 μm or less.

[0016]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

Example 1 Zirconia powder, ceria powder, yttria powder, calcia powder, magnesia powder and lanthanum powder having a purity of 99.9% or more were mixed in the composition shown in Table 1 and the mixture was rubber-pressed at ² ton / cm ^2. After molding in an oxygen stream,
Firing was performed at 1500 ° C. to obtain a sintered body.

Three-point bending strength, fracture toughness, crystal phase, average grain size, and hydrothermal deterioration characteristics of this sintered body were measured. The results are shown in Table 2. As a comparative example, zirconia partially stabilized with 3 mol% yttria was also evaluated, and the result is shown in No. 13.

The values in Table 2 are based on the following method.

1) Three-point bending strength: Measured at a load speed of 0.5 mm / min according to JIS standard.

2) Fracture toughness value: According to IF method.

3) Crystal phase: monoclinic, (-111),
Diffraction intensity of (111) plane Tetragonal crystal, Diffraction intensity of (111) plane Cubic crystal, Diffraction intensity of (111) plane 4) Average particle size; SEM photograph based on planometric method (excluding alumina particle size) 5 ) Hydrothermal deterioration characteristics: Measured at 170 ° C. under a steam of 7 kg / cm ² after 24 hours for a change in monoclinic crystal ratio.

[0023]

[Table 1]

[0024]

[Table 2]

Example 2 A ferrule material was produced by an injection molding method using powders having the compositions shown in Nos. 1 and 4 of Table 1, and further processed. Regarding inner core processing, outer peripheral processing, and lapping, the processing time was compared with that of the conventional 3Y-based zirconia material (No. 15). The results are shown in Table 3. From this, it was found that the processing time can be shortened in any processing process. In addition, the yield of processed products is over 95%,
It was found that even when compared with 70 to 90% of 3Y zirconia, it was significantly improved.

Example 3 A ferrule material was manufactured by an injection molding method using powder having the composition shown in No. 4 of Table 1, further processed, and a ferrule was attached to the ferrule material to assemble it as an optical fiber connector.
When PC polishing was performed, the quartz fiber was dented from the connector by polishing, and the "fiber withdrawal amount" was 0.05 µm or less, which was much less than 0.10 µm or less in the case of No. 15 3Y-based zirconia. .
This is because, as shown in Table 5, the hardness of Ce-based zirconia is closer to the hardness of quartz fiber than that of 3Y-based zirconia.

Example 4 Using a powder having the composition shown in No. 3 in Table 1, a ferrule material was manufactured by an extrusion molding method, and this was further processed and attached with a flange and the like to assemble it as an optical fiber connector, and to prepare an optical cord. Insertion loss and return loss were measured.
Further, 3Y zirconia (No. 15) was also evaluated in the same manner. The results are shown in Table 4.

From these results, it was found that all the samples sufficiently satisfied the reference value and that there was almost no problem in actual use.

[0029]

[Table 3]

[0030]

[Table 4]

[0031]

[Table 5]

[0032]

As is apparent from the above description, the optical connector part according to the present invention is excellent in workability and environmental resistance.

[Brief description of drawings]

FIG. 1 shows a structural diagram of an SC type optical connector. The plugs to which the ferrules are fixed are respectively inserted from both ends of the adapter through the split sleeves to connect the fibers.

FIG. 2 is a simplified cross-sectional view of a ferrule processed material of the optical connector parts of the present invention. The inner diameter is 126 μm, and the optical fiber passes therethrough.

FIG. 3 is a schematic view of a split sleeve processed material of the optical connector component of the present invention. The inner diameter is slightly smaller than the outer diameter of the ferrule, so that the ferrule can be held elastically.

4 is a No. 15 3Y-based zirconia of Example 1 and No.
It is an enlarged view (100 times) when an indent is imprinted by the Vickers hardness meter about Ce type zirconia of No. 1. It can be seen that there is a large difference in the crack generation status.

5 is a No. 15 3Y-based zirconia of Example 1 and No
The Ce-based zirconia of No. 4 was injection-molded to make a ferrule material, which was further processed and then 170 ° C.
It is exposed to the saturated vapor of No. 1 and the time-dependent change of the phase transition from the tetragonal system to the monoclinic system at the surface part is obtained. It can be seen that in the case of the 3Y system, the phase transition rapidly occurs, whereas in the Ce system, there is almost no change.

[Explanation of symbols]

1: Adapter part 2: Plug part 3: Ferrule
4: Sleeve

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Etsuji Sugita 1-3-3 Gotenyama, Musashino City, Tokyo NTT Advanced Technology Co., Ltd. (72) Inventor Yuichi Shimizu Musashino City, Tokyo Gotenyama 1-3-3 NTT Advanced Technology Co., Ltd. Inside the company (72) Inventor Yasuhiro Ando 1-1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (1)

[Claims] 1. A connector for connecting an optical fiber,
A ferrule having pores for inserting and holding an optical fiber,
A component for an optical fiber connector, characterized in that a sleeve for connecting and holding the same is mainly formed of zirconia ceramics having cerium oxide as a stabilizer.