JPS581360B2 - Kaitenchikunetsushiki Netsukou Kankiyo Seal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a seal for use in a rotating regenerative heat exchanger for a gas turbine engine.

Conventionally, this type of seal is made of austenitic stainless steel base metal 1 (for example, SUS304) as shown in Figure 1.
Then, a nickel aluminide base bonding material layer 2 (Meteco 404, 450, etc.) is thermally sprayed, and on top of that, a blend of nickel oxide and calcium fluoride is sprayed using plasma at a temperature of 2000°C or higher to create a wear-resistant sliding surface. 3 and is configured.

However, such conventional seals, especially when used on the high temperature side of a heat exchanger, often peel off at a point A where the wear-resistant sliding surface 3 slightly penetrates from the base bonding material layer 2.

This peeling occurs because the amount of thermal expansion of the base metal 1 is larger than that of the sliding surface 3, and the difference in thermal expansion cannot be absorbed by the base bonding material layer 2, so that the sliding surface 3 This is because it cannot follow the growth.

In reality, the coefficient of thermal expansion of the blend sprayed layer of nickel oxide and calcium fluoride that constitutes the sliding surface 3 is the same as that of the austenitic stainless steel that constitutes the base metal 1 (approximately 1
5X10-6/°C).

Therefore, ferritic stainless steel whose coefficient of thermal expansion is relatively close to that of the above-mentioned blended sprayed layer (approximately 10×lO-1/°C
) or martensitic stainless steel as the base metal 1, or spraying it on the austenitic base metal 1 as shown at 4 in Figure 2 was considered, but emphasis was placed on corrosion resistance in a high temperature atmosphere. In this case, it is preferable to use austenitic stainless steel as the base metal 1, and in fact, this type of stainless steel is generally used.

The present invention proposes an improved seal for an alternative rotary regenerative heat exchanger, focusing on the fact that nickel oxide has metallic properties and is strong, and calcium fluoride has ceramic properties and is fragile. This embodiment embodies the idea of increasing the peel strength of the sliding surface by setting the nickel oxide spraying ratio on the sliding surface to be highest on the base metal 1 side and gradually decreasing as the distance from the base metal 1 increases.

That is, in the present invention, as shown in FIG. 3, for example, a layer 5 of only nickel oxide is first formed on a base bonding material layer 2 (0.01 mm thick) of nickel aluminide that is thermally sprayed on a base metal 1 with a thickness of 2 mm. (thickness: 0.1 m), on top of which layer 6 (thickness: 0.1 mm) of 90% nickel oxide and 10% calcium fluoride, and further on top of that, so% nickel oxide and calcium fluoride. 20% layer 7 (thickness 0.5
~0.7 mm) to form the sliding surface 3 in three layers.

Then, the thickness of the final sprayed layer 7 is made several times thicker than the previous sprayed layer.

Therefore, in the seal of the present invention, the portion of the sliding surface 3 adjacent to the base metal 1 that is easily peeled off has high mechanical strength, and it is possible to make the sliding surface 3 difficult to peel off without sacrificing wear resistance. can.

In addition, the final sprayed layer is several times thicker than the previous sprayed layer and is porous, so it can quickly complete the initial break-in during sliding contact with the heat exchanger and achieve the sealing effect quickly. can.

In addition, as a result of the experiment, the sliding surface 3 of the conventional seal shown in Fig. 1 peeled off in an operating atmosphere of 700°C, and the seal sliding surface 3 of Fig. 2 peeled off in an operating atmosphere of 750°C. On the other hand, in the seal of the present invention, it was confirmed that the sliding surface 3 did not peel off even under a temperature condition of 800°C.

Furthermore, it goes without saying that the same effects as described above can be obtained when the base metal 1 is martensitic stainless steel or ferrite stainless steel.

[Brief explanation of drawings]

Figures 1 and 2 are sectional views showing two examples of conventional seals;
FIG. 3 is a sectional view showing an embodiment of the seal of the present invention. DESCRIPTION OF SYMBOLS 1... Base metal, 2... Substrate bonding material layer, 3... Sliding surface, 5-7... Sliding surface constituting layer.

Claims (1)

[Claims] 1. A rotating regenerative heat exchanger in which a base bonding material layer of nickel aluminide is thermally sprayed onto a stainless steel base metal, and a blend of nickel oxide and calcium fluoride is sprayed onto the base bonding material layer to form a sliding surface. In the dexterity seal,
The sliding surface is composed of a plurality of thin layers, and among these thin layers, the layer closest to the base metal is a sprayed layer of only nickel oxide, and the other thin layers are sprayed layers of nickel oxide and calcium fluoride. , the proportion of nickel oxide in each of the other thin layers is gradually reduced so that the layer farther from the base metal is smaller, and the thickness of the final sprayed layer furthest from the base metal is the same as that of the previously sprayed layer. A seal for a rotary heat storage type heat exchanger, characterized by being formed several times thicker.