This standard specifies the terms and definitions, grades, technical requirements, test methods, quality evaluation procedures, packaging, marking, transportation, storage, and quality certificates for alumina bubble bricks.
This standard applies to alumina bubble bricks used in high-temperature industrial kilns.
The following documents are essential for the application of this standard. For dated references, only the edition cited applies. For undated references, the latest edition (including all amendments) applies.
A shaped refractory product made from alumina hollow spheres and α-Al₂O₃ powder as primary raw materials, formed and fired at high temperatures. It contains more than 90% Al₂O₃, with α-Al₂O₃ (corundum) as the main crystalline phase.
Alumina bubble bricks are classified into nine grades based on alumina content and bulk density: LQZ-99-1.4, LQZ-99-1.6, LQZ-99-1.8, LQZ-95-1.4, LQZ-95-1.6, LQZ-95-1.8, LQZ-90-1.4, LQZ-90-1.6, and LQZ-90-1.8.
In the grade designation, “L”, “Q”, and “Z” are the initials of the Chinese pinyin for “alumina”, “bubble”, and “brick”. The numbers 99, 95, and 90 indicate the percentage of alumina content, and 1.4, 1.6, and 1.8 represent the bulk density.
5.1 The physical and chemical properties of alumina bubble bricks shall comply with the specifications in Table 1.
Table 1: Physical and Chemical Properties of Alumina Bubble Bricks
5.2 The dimensional tolerances and appearance of alumina bubble bricks shall meet the requirements of Table 2, with units in millimeters.
Table 3: Dimensional Tolerances and Appearance of Alumina Bubble Bricks
5.3 Special technical requirements shall be agreed upon by the supplier and the customer.
6.1 Sampling for testing shall follow GB/T 7321. For special-shaped products that cannot provide standard test samples, straight bricks made under the same process conditions shall be used instead.
6.2 Chemical composition shall be determined according to GB/T 6900 or GB/T 21114.
6.3 Bulk density shall be tested as per GB/T 2998.
6.4 Cold crushing strength shall be measured following GB/T 5072.
6.5 Permanent linear change upon heating shall follow GB/T 5988.
6.6 Thermal conductivity shall be tested according to YB/T 4130.
6.7 Dimensional and appearance inspection shall be conducted in accordance with GB/T 10326.
Products shall be grouped into batches based on the same grade, with each batch not exceeding 100 tons.
Sampling shall be conducted in accordance with GB/T 10325.
Chemical composition, bulk density, cold crushing strength, thermal conductivity, and permanent linear change upon heating are the mandatory inspection items. Test results shall comply with the specifications in Table 1.
If any non-conformance is found, double the number of samples shall be retested for the specific item. The batch shall be deemed acceptable if the average of the retest results meets the requirements of Table 1. Otherwise, the batch shall be rejected.
Conformity assessment may be carried out through supplier declarations, customer validation, or third-party certification.
8.1 Packaging, marking, transportation, and storage shall comply with GB/T 16546, or as specified in the contract.
8.2 A quality certificate issued by the supplier’s quality control department shall accompany the product upon delivery. The certificate shall include the supplier’s name, customer’s name, product name and grade, contract number, production date, and results of physical and chemical property tests.
