High temperature corrosion of anchor systems for refractory constructions at different atmospheres and temperatures

1 Reasons for plant failures [1]

2 The initial state of the tested materials under the optical microscope; grinded and etched, 500-times magnified (500x)

3 Experimental setup for the annealing tests in reactive atmospheres

4 Results at a reducing atmosphere for 100 hours, LOM, 500x

5 Results at a nitriding atmosphere for 200 hours at 700 °C and 1000 °C respectively; LOM, 500x

6 2.4851, 200 h, 1000 °C, SO₂, microprobe

7 1.4864, 200 h, 1000 °C, SO₂, microprobe

8 1.4862, 200 h, 1000 °C, SO₂, microprobe

9 1.4845, 200 h, 1000 °C, SO₂, microprobe

10 1.4828, 200 h, 1000 °C, SO₂, microprobe

11 2.4851, 200 h, 1000 °C, Cl2, microprobe

12 1.4864, 200 h, 1000 °C, Cl₂, microprobe

13 1.4862, 200 h, 1000 °C, Cl₂, microprobe

14 1.4845, 200 h, 1000 °C, Cl₂, microprobe

15 1.4828, 200 h, 1000 °C, Cl₂, microprobe

Kiln inlet trough

Summary: High temperature corrosion decisively influences the durability of anchorage systems in refractory constructions. Five different materials, which are used as refractories, have been tested and compared with respect to their corrosive properties in reducing, nitriding, carborizing, sulfidizing/oxidizing, and chlorinating media at different temperatures and times of deposition. The metallographic pictures of the withdrawn samples are compared in order to evaluate the stage of corrosion. The materials are finally rated for their suitability in the corresponding medium.

1 Introduction

Highly heat resisting and high-alloyed steels, as well as nickelbased alloys are used for building chemical and metallurgic plants. These materials are used in anchorages and refractory constructions, where high temperatures occur. Within these areas, the metal components are prone to chemical reactions, since the media are not clear of aggressive elements. In case of failure the refractory breaks out of the construction. A DGFS ¹ survey asked plant operators about the reasons for failure (Fig. 1).

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