Details

Definition

Nuclear grade boron carbide is one of the engineering ceramic materials used in the nuclear industry aspect, which can absorb neutrons and prevent radiation widely, and is applied in the shielding materials of atomic reactor isolation control rods and nuclear power plants, which is a national key material for development. In addition, boron carbide is an important neutron absorbing material in the nuclear industry.

Testing items

Nuclear grade boron carbide testing items: total boron, total carbon, soluble boron, isotope analysis (mass spectrometry), free carbon, iron, aluminum, silicon, calcium, cobalt, chromium, copper, magnesium, manganese, molybdenum, phosphorus, nickel, titanium, tungsten, zirconium, and fluorine, chlorine, and other chemical components.

Testing standards

Nuclear grade boron carbide testing standards: ASTM C791-2019 “nuclear grade boron carbide chemical, mass spectrometry and spectroscopy analysis standard methods”, JB/T 7993-2012 boron carbide chemical analysis methods, YS/T 423.1 ~ 5-2000 series of standards, “nuclear grade boron carbide powder chemical analysis methods”.

Overview of Boron Carbide

General abrasive boron carbide – as one of the three hardest known materials (after diamond and cubic phase boron nitride), suitable for grinding, lapping and polishing of hard materials, such as super-hard alloys, gemstones and other hard materials, ceramic wear-resistant parts, including wear reinforcement plates, pump parts, bearings, nozzles, valve parts, engineering ceramics (including structural, environmental and process ceramics) and so on. In addition, boron carbide is an important neutron absorption material in the nuclear industry, also known as nuclear grade boron carbide. Chemical composition is the key factor affecting the use of boron carbide performance, the production and application of the product has an important guiding significance.

Different use occasions corresponding to the composition indicators are different. Among them, JB/T 3294-2017 “general abrasives boron carbide” in the requirements of the particle size as shown in Table 1.

 Table 1 The chemical composition of the products of each particle size number

In the relevant standards and specifications of the nuclear industry, the technical indicators of boron carbide have detailed provisions, mainly “ASTM C750-2018 Standard Specifification for Nuclear-Grade Boron Carbide Powder” and “EJ/T20077-2014 Lead Boron Polyethylene Sheet”, the specific index requirements are shown in Table 2 and Table 3.

Table 2 Technical requirements of nuclear-grade boron carbide

Table 3 Indicator requirements for boron carbide for lead boron polyethylene sheet

Different chemical analysis methods

1. General abrasive boron carbide chemical composition analysis is mainly based on “JB/T 7993-2012 boron carbide chemical analysis method” standard test, the standard is mainly analyzed in the boron carbide samples of total boron, total carbon, iron oxide, silicon dioxide, boron oxide, free boron, free carbon and other 7 items. From the standard can be seen in the total boron, total carbon, diboron trioxide, free boron, free carbon is the focus of boron carbide analysis and detection. Due to the existence of different isomers of boron carbide belonging to non-chemical compounds, the detection of B4C content is mainly calculated by the content of chemical boron and chemical carbon.

2. Nuclear grade boron carbide analysis is mainly based on the “ASTM C791-2019” nuclear grade boron carbide chemical, mass spectrometry and spectroscopy analysis standard “standard test, the standard specifies total boron, total carbon, soluble boron, isotope analysis (mass spectrometry), free carbon, iron, aluminum, silicon, calcium, cobalt, chromium, copper, magnesium, manganese, molybdenum, phosphorus, nickel, titanium, tungsten, zirconium, and fluorine, chlorine, and other chemical composition testing methods. The standard test items cover the technical indexes of nuclear grade boron carbide, which provides the testing basis and methods for the relevant users in the nuclear industry.

3. Domestic nuclear-grade boron carbide standards are mainly YS/T 423.1-5-2000 series of standards, “Chemical Analysis Methods for Nuclear-Grade Boron Carbide Powder”, with the main items of total boron, total carbon, iron, free boron, oxygen content and other five items. This series of standards covers the detection of oxygen content in boron carbide samples, and provides testing methods for nuclear grade boron carbide powder and core block.