Casting product having alumina barrier layer

A technology of aluminum oxide and barrier layer, which is applied in coating, manufacturing tools, solid-state diffusion coating, etc., can solve the problems of reduced wood ductility, achieve the effects of inhibiting coking, improving operating efficiency, and reducing the number of times

Active Publication Date: 2017-02-22
KUBOTA LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Therefore, even if the austenitic heat-resistant alloy of the above-mentioned patent document can be expected to be made of Al 2 o 3 The improvement of the blocking function brought about, but there is also a bad phenomenon that leads to the reduction of the ductility of the wood

Method used

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  • Casting product having alumina barrier layer
  • Casting product having alumina barrier layer
  • Casting product having alumina barrier layer

Examples

Experimental program
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Effect test

Embodiment 1

[0093] The molten metal was smelted by atmospheric melting in a high-frequency induction heating melting furnace, centrifugally cast through a mold, and a pipe body with the chemical composition of the alloy shown in Table 1 below was cast. The tube body has an inner diameter of 80mm, an outer diameter of 100mm, and a length of 250mm.

[0094] [Table 1]

[0095] .

[0096] The obtained Examples 1 to 8 and Comparative Examples 1 to 6, which are examples of the invention, were subjected to two-step heat treatment in an oxidative atmosphere with different heating temperatures. Heat treatment is performed first at low temperature and then at high temperature. The low temperature heat treatment is 5 hours, and the high temperature heat treatment is 5 hours.

[0097] [Table 2]

[0098] .

[0099] For the test tubes of Examples 1 to 8 and Comparative Examples 1 to 6 subjected to heat treatment, the elements contained in the aluminum oxide barrier layer formed on the surface ...

Embodiment 2

[0119] In Invention Example 2 and Invention Example 7, TEM observation of the film of the alumina barrier layer was performed using a transmission microscope (TEM). In addition, EDX analysis was performed on the Al thin layer and the Al concentrated layer, respectively. The result of Invention Example 2 is shown in Figure 4 , the results of Invention Example 7 are shown in Figure 5 .

[0120] refer to Figure 4 It can be seen that the thin Al layer 22 formed on the surface side in Invention Example 2 is mainly Al oxides, but small amounts of Cr, Fe, and Ni were observed. On the other hand, Cr, Fe, Ni, etc. other than Al were not observed in the Al concentrated layer 24 . From this, it can be seen that the Al concentrated layer 24 is formed of extremely high-purity aluminum oxide.

[0121] refer to Figure 5 It can be seen that the thin Al layer 22 formed on the surface in Inventive Example 7 is mainly Al oxide, but a small amount of Cr was observed. On the other hand,...

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Abstract

The present invention provides a casting product which has an alumina barrier layer having further improved stability, and can exhibit superior oxidation resistance, carburization resistance, nitridation resistance, corrosion resistance and the like when used under high-temperature atmospheres. The casting product according to the present invention is one having an alumina barrier layer which is formed on the surface of a base and contains an aluminum oxide, wherein the aluminum oxide is represented by the formula: (Al(1-x)M(x))2O3 wherein M represents at least one element selected from Cr, Ni, Si and Fe and 0 < x < 0.5. The casting product according to the present invention is also one having an alumina barrier layer which is formed on the surface of a base and contains an aluminum oxide, wherein the aluminum oxide contains at least one element selected from Cr, Ni, Si and Fe which is dissolved in the form of a solid solution, and wherein the content ratio, in at.%, of at least one element selected from Cr, Ni, Si and Fe which is dissolved together with Al in the form of a solid solution satisfies the formula: Al / (Cr+Ni+Si+Fe) >= 2.0.

Description

technical field [0001] The present invention relates to castings having an alumina barrier, and more particularly to castings having a structurally stable alumina barrier. Background technique [0002] Heat-resistant steel castings such as reaction tubes and decomposition tubes for ethylene production, hearth rolls of carburizing heat treatment furnaces, radiant tubes, and metal dusting-resistant materials are exposed to high-temperature atmospheres, so high-temperature strength is used Excellent austenitic heat-resistant alloy. [0003] When this austenitic heat-resistant alloy is used in a high-temperature atmosphere, a metal oxide layer is formed on the surface, and the oxide layer acts as a barrier to protect the base material in a high-temperature atmosphere. [0004] On the other hand, as these metal oxides, if Cr oxides (mainly composed of Cr 2 o 3 Composition), the density is low, so the function of preventing oxygen and carbon intrusion is insufficient, and inter...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C8/14C22C19/05C22C30/00C22C38/00C22C38/58C21D6/00C22F1/00C22F1/10
CPCC21D6/004C23C8/14C22C19/05C22C30/00C22C38/58C22F1/00C22F1/10C21D9/14C21D1/68C21D1/70C21D2251/02C23C8/80C22C19/055C22C19/056B22D13/02C22C38/005C22C38/02C22C38/04C22C38/06C22C38/44C22C38/48C22C38/50C22C38/54C23C8/10
Inventor 桥本国秀浦丸慎一
Owner KUBOTA LTD
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