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Composition gradient cermets and reactive heat treatment process for preparing same

a technology of gradient cermets and reactive heat treatment, applied in the field of cermets, can solve the problems of reducing the protection of the internals of the vessel, exposing the internals of the refinery process vessel to aggressive fluids containing hard solid particles such as catalyst particles, and reducing the production cos

Inactive Publication Date: 2008-10-23
EXXON RES & ENG CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The patent describes a process for making a material with a graded composition, called cermet. This process involves heating a metal alloy containing chromium and titanium, and then exposing it to a reactive environment containing carbon, nitrogen, or other elements. The heated alloy is then cooled to a lower temperature to create the cermet material. The resulting material has a graded composition, meaning it has different compositions in different parts. This process can create materials with improved properties like high strength and durability.

Problems solved by technology

For example, refinery process vessel internals exposed to aggressive fluids containing hard solid particles such as catalyst particles in various chemical and petroleum environments are subject to both erosion and corrosion.
The protection of these vessel internals against erosion and corrosion induced material degradation especially at high temperatures is a technological challenge.
The life span of these refractory liners is significantly limited by mechanical attrition of the liner, cracking and spallation.

Method used

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  • Composition gradient cermets and reactive heat treatment process for preparing same
  • Composition gradient cermets and reactive heat treatment process for preparing same
  • Composition gradient cermets and reactive heat treatment process for preparing same

Examples

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Effect test

example 1

Reactive Heat Treatment of Commercial Alloys

[0053]The reactive heat treatments were conducted on the selected chromium containing commercial alloys, 304SS, 310SS, Haynes HR120 and Inconel 353MA. The nominal compositions are given below.

TABLE 1Compositions of Chromium Containing Commercial AlloysUNSAlloysNo.Composition (wt %)304 Stainless SteelS30400Bal Fe:18.5Cr:9.6Ni:1.4Mn:0.6Si310 Stainless SteelS31000Bal Fe:25.0Cr:21.0Ni:1.5Si:2.0MnHaynes HR120N08120Bal Fe:33.0Cr:37.0Ni:2.5Mo:2.5W:0.6SiInconel 353MAS35315Bal Fe:24.8Cr:34.8Ni:1.6Si:1.4Mn

[0054]The samples had rectangular geometry with dimensions of about 1.25 cm×1.25 cm×1 cm. The sample surfaces were ground to a 600 grit SiC finish and cleaned ultrasonically in acetone. The procedure used in the invention was to establish the kinetics of carburization of the selected alloys in a purely carburizing environment (CH4—H2), which was determined thermogravimetrically in a Cahn 1000 thermogravimetric unit. The investigations were carried ...

example 2

Reactive Heat Treatment of Commercial Alloys

[0056]The chromium containing alloys listed above were reactively heat treated in a tube furnace for 24 hours at 1100° C. in 10 vol % CH4:90 vol % H2 environment. Samples were heated to a temperature of 1100° C. in a hydrogen environment and held at that temperature for approximately 5 minutes. After 24 hours of exposure, the alloy samples were cooled down. After the samples reached room temperature (25° C.), the surface microstructure and the thickness of cermet layer formed on various alloy surfaces were investigated by cross sectional scanning electron microscopy. Chemical compositions of M7C3 carbide phase and Cr-depleted binder phase were investigated by semi-quantitative energy dispersive x-ray spectroscopy. The tendencies of Fe and Ni to partition between the metal matrix and the carbide precipitates are expected to be different. The thickness of cermet layers, Cr and Fe contents in M7C3 carbide phase and composition of Cr-depleted ...

example 3

Reactive Heat Treatment of Custom-Made Alloys

[0057]Alloys containing different concentrations of Fe, Ni, Cr and Ti were prepared by arc melting. The arc-melted alloy buttons were annealed at 1100° C. overnight in inert argon atmosphere and furnace-cooled to room temperature. Cubical samples of about 1.25 cm×1.25 cm×0.75 cm were cut from the buttons. The sample faces were polished to 600-grit finish and cleaned in acetone. The specimens were exposed to a 10 vol % CH4:90 vol % H2 gaseous environment at 1100° C. for 24 hours.

[0058]Detailed electron microscopy and chemical analysis of the alloys after exposure indicated that specific alloy compositions in the Fe—Ni—Cr system generate cermet structure with M7C3 carbide and metal phase. The thickness of cermet layers, Cr and Fe contents in M7C3 carbide phase and compositions of Cr-depleted metal matrix phase within cermet layers are summarized in Table 3. By contrast to the example of selected commercial alloys, relatively thick cermet la...

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Abstract

Cermets, particularly composition gradient cermets can be prepared starting with suitable bulk metal alloys by a reactive heat treatment process involving a reactive environment selected from the group consisting of reactive carbon, reactive nitrogen, reactive boron, reactive oxygen and mixtures thereof.

Description

[0001]This application claims the benefit of U.S. Provisional application 60 / 471,992 filed May 20, 2003.FIELD OF INVENTION[0002]The present invention is broadly concerned with cermets, particularly composition gradient cermets and reactive heat treatment process for preparing same.BACKGROUND OF INVENTION[0003]Erosion resistant materials find use in many applications wherein surfaces are subject to eroding forces. For example, refinery process vessel internals exposed to aggressive fluids containing hard solid particles such as catalyst particles in various chemical and petroleum environments are subject to both erosion and corrosion. The protection of these vessel internals against erosion and corrosion induced material degradation especially at high temperatures is a technological challenge. Refractory liners are used currently for components requiring protection against the most severe erosion and corrosion such as the inside walls of cyclones such as the internal cyclones in flui...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C23C8/00
CPCC23C8/22
Inventor CHUN, CHANGMINBANGARU, NARASIMHA-RAO VENKATAJIN, HYUN-WOOKOO, JAYOUNGPETERSON, JOHN ROGERANTRAM, ROBERT LEEFOWLER, CHRISTOPHER JOHN
Owner EXXON RES & ENG CO
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