METHOD FOR DETERMINING RESIDUAL LIFE OF POROUS AND COMPOSITE CERAMIC LINING MATERIALS OF HIGH-TEMPERATURE FURNACES Russian patent published in 2024 - IPC G01N3/60 C21B7/24 

FIELD: measuring.

SUBSTANCE: invention relates to methods of non-destructive testing and is intended for determination of residual service life of porous and composite materials in multi-layer lining of high-temperature furnaces or units. Method includes test of material sample for temperature dependence of thermal expansion and creep, determining the temperature T_pd of the beginning of plastic deformation under a standard load of 0.2 MPa and determining the activation energy Q of the material taking into account the rate of recrystallization by selecting in the computer animation mode the activation energy Q, at which an increase in the rate of recrystallization with increasing temperature T occurs at the temperature of the onset of plastic deformation T_pd, photographing by means of an optical microscope coupled with a computer of the selected treated portion of the investigated material on the surface of the article, determining the grain size of the analysed material by micrographs, determining the average grain size by computer analysis of experimental data, determination of quantum number k1 by average grain size of analysed material structure, determining the quantum number k2 in range of 0.75-0.85 depending on the maximum grain size established from the known reference data for the analysed material, multiplier value calculation τ_o by using as lower and upper limits of integration of quantum numbers k1 and k2 respectively

by formula

where: τ₀ is a multiplier depending on the grain growth history of the material before the start of operation and during the operation through the integral of the function of the quantum number k; k is the material granular structure quantum number; k1 is the quantum number determined from the average grain size of the structure of the analysed material; k2 is a quantum number defined in range of 0.75-0.85 depending on the maximum grain size established from the known reference data for the analysed material. Then durability is calculated τ investigated material taking into account thermal and mechanical loads by formula:

where: τ is durability of the analysed material, days; τ₀(k1,k2) is a factor depending on the grain growth history of the material before the start of operation and during the operation through the integral of the function of the quantum number k; Q is activation energy, J/mol; σ is tension tensor component, Pa; ε is component of deformation tensor, %; ϑ is molar volume of material, m³/mol; R is universal gas constant, J*mol^-1*K^-1; D₀ is constant of coefficient of thermal diffusion of atoms or molecules in polycrystalline material, J^-1*s^-1; α is constant of binding energy of paired valence electrons, determining covalent or ionic bond of atoms or molecules in polycrystalline material, J/K; Tc is material melting point, °C; T is material operating temperature during the period of time of the estimated aging of the material, °C.

EFFECT: high accuracy of determining residual life of porous and composite ceramic materials.

1 cl, 13 dwg