Crack Formation Mechanism in Centrifugal SHS Ceramic Composite Steel Pipe - Literature Study Note

Literature Overview

This paper by Zhang Shuguang, Zhang Baoping, and Wang Kezhi from the Beijing General Research Institute for Nonferrous Metals, Baoshan Iron and Steel Company, and Beijing University of Science and Technology investigates the crack formation mechanism in centrifugal SHS (solid homogeneous suspension) ceramic composite steel pipes during the cooling process. Published in the Journal of the Chinese Ceramic Society in 1999, this work addresses a critical manufacturing quality issue in the production of ceramic-lined steel pipes used in severe abrasion and corrosion environments.

Manufacturing Process Context

The centrifugal SHS process involves the following key steps:

A steel pipe is heated and rotated at high speed.
A ceramic slurry (solid homogeneous suspension) is introduced into the rotating pipe.
Centrifugal force distributes the slurry uniformly against the pipe inner wall.
The slurry sinters and bonds to the steel pipe during subsequent cooling.
The resulting composite pipe has a ceramic inner lining bonded to the steel outer structure.

The cooling stage is critical because differential thermal contraction between the ceramic layer and the steel pipe generates significant residual stresses that can cause cracking.

Crack Classification and Mechanism

The paper proposes a novel classification of ceramic layer cracks based on the mechanical cause of formation:

Crack Type	Formation Mechanism	Temperature Stage	Stress State
Tensile crack (张裂纹)	Ceramic layer in tension due to differential contraction	High temperature cooling	Tensile stress exceeds ceramic tensile strength
Compressive crack (压裂纹)	Ceramic layer in compression from steel pipe contraction	Intermediate temperature	Compressive stress exceeds ceramic compressive strength
Quasi-compressive crack (准压裂纹)	New concept proposed in this paper	Specific temperature range	Combined stress state near compressive limit

The introduction of the "quasi-compressive crack" (准压裂纹) concept is a significant theoretical contribution. This crack type forms under a stress state that is not purely compressive but approaches the compressive failure limit of the ceramic material, representing a transitional failure mode.

Numerical Simulation and Temperature Field Analysis

The study employs numerical simulation of the temperature field during cooling to analyze the evolution of temperature, dimensions, and stress in each layer of the composite pipe. Key findings from the simulation include:

The temperature gradient between the ceramic layer and the steel pipe is the primary driver of thermal stress development.
The cooling rate of the steel pipe significantly affects the stress state in the ceramic layer.
The ceramic layer experiences a complex stress history during cooling, transitioning between tensile and compressive states at different temperature stages.

The concept of a "cooling hologram" (冷却全息图) is introduced — a comprehensive diagram that summarizes the crack formation behavior across the entire cooling process, providing a unified visual framework for understanding crack mechanisms.

Technical Parameters and Process Control

For steel pipe manufacturers producing ceramic composite pipes, the following process parameters are critical:

Process Parameter	Effect on Crack Formation	Control Strategy
Cooling rate of steel pipe	Faster cooling increases thermal stress in ceramic	Controlled cooling atmosphere or rate
Ceramic layer thickness	Thicker layers experience higher thermal gradients	Optimize thickness for application requirements
Ceramic material thermal expansion coefficient	Higher coefficient increases differential contraction	Select ceramic with matched thermal expansion
Steel pipe material	Affects steel contraction rate and final dimensions	Select steel with appropriate thermal properties
Initial ceramic layer temperature	Affects stress development during cooling	Optimize sintering and cooling schedule

Engineering Practice and Quality Control Implications

The research findings have direct implications for manufacturing quality control:

The identification of thermal stress and steel pipe compressive force as the two primary causes of ceramic layer cracking provides clear targets for process optimization. Controlling both the ceramic layer properties and the steel pipe cooling rate is essential.
The crack classification system enables more systematic defect analysis during quality inspection. By identifying the crack type, manufacturers can trace the root cause to specific process stages and implement targeted corrective actions.
The cooling hologram provides a practical tool for process engineers to predict and prevent crack formation by optimizing the cooling schedule. This is analogous to a process capability analysis in traditional manufacturing quality management.
For non-destructive testing of ceramic-lined steel pipes, the crack type information is valuable for selecting appropriate inspection methods — for example, ultrasonic testing may be more effective for through-thickness cracks while eddy current methods may detect surface and near-surface defects.

Study Insights and Reflections

This research represents a valuable contribution to the understanding of ceramic-steel composite pipe manufacturing, particularly in identifying the complex stress evolution during cooling and proposing a comprehensive crack classification system. The practical significance is considerable for industries relying on ceramic-lined steel pipes — including mining, cement, chemical processing, and power generation — where abrasion-resistant and corrosion-resistant linings are essential for equipment longevity. The key insight is that crack prevention requires a holistic approach that addresses both the ceramic material properties and the steel pipe thermal behavior, rather than focusing on either component in isolation. For steel pipe manufacturers entering the ceramic composite pipe market, understanding these fundamental crack formation mechanisms is essential for developing reliable manufacturing processes and achieving consistent product quality. The cooling hologram concept, in particular, offers a powerful analytical framework that can guide process development and optimization for different ceramic-steel material combinations.