In the past decades, compact shielding design has attracted widespread attention with the miniaturization and optimization of nuclear reactors, which were used to protect human health and improve equipment safety from potential neutron radiation. Owing to the limits of space, neutron shielding materials (NSMs) usually have to service in quite inclement environment with high temperature, corrosion, and so on. H
3BO
3 solution has been widely used in nuclear reactors as a moderator, and the concentration of H
3BO
3 became higher and approaches saturation due to the limitation of space. Considering the long-term service of NSMs in H
3BO
3 solution, the corrosion behavior had a great influence on the reliability of the materials. Thus, high performance NSMs with high mechanical strength and low acid corrosion rate were needed [
1,
2].
In general, concrete, alloy plate, polyethylene, as well as B
4C ceramics have been widely used as NSMs. However, they fall short in some aspects for compact shielding design, such as space consumption, toxicity, poor acid corrosion resistance, poor thermal stability, and synthesis difficulties [
3,
4,
5]. Therefore, developing novel NSMs with better properties has become urgent in the research of neutron radiation protection. Of particular note is that a compound with boron content can serve as an NSM, owing to its ability to capture thermal neutrons due to a huge thermal neutron absorbing cross section (3838.1 b) of isotope
10B [
6]. BPO
4 glass containing Li
2O, Al
2O
3, ZnO
2, PbO, and Bi
2O
3 had already been proved to posses excellent neutron shielding performance [
7]. In addition, the ceramic materials usually have excellent characteristics such as high mechanical strength, good thermal stability, and superb corrosion resistance. The BPO
4 ceramics (BPCs) had been prepared via SPS using H
3BO
3 and NH
4H
2PO
4 as raw materials and had superb thermal stability at 1200 °C [
8]. However, NH
3 would be produced in this method, which causes pollution. As an acidic compound, neutralization reaction would not occur between BPO
4 and acid solution. In this regard, BPCs should have enormous potential used in compact shielding design. Nevertheless, no related research focusing on using BPCs as NSMs have been reported. The mechanical/thermal properties and acid corrosion resistance have not been discussed. BPO
4 has already been successfully synthesized by a variety of techniques including liquid-phase precipitation, sol-gel method, hydrothermal method, and so on [
9,
10]. Certainly, the cost of NSMs was also an important requirement to be considered.
In this work, BPCs was fabricated via a two-step route. First, BPO4 powders were synthesized by H3BO3 and H3PO4. The raw materials were mixed and pre-heated, ensuring that H3BO3 and H3PO4 were completely decomposed to minimize the porosity of the obtained final products. Then, these powders were used as precursor to be modeled, and the green body used a pressureless sintering method to prepare BPCs. Compared with the B4C ceramics that need to be sintered over 2000 °C and the BPCs prepared by SPS, the BPCs prepared in this work were low in sintering temperature, simple in process, and require less equipment, thereby effectively reducing the preparation cost. In the case of changing the calcination temperature and H3BO3 content, phase composition and microstructure, as well as the mechanical, thermal, neutron shielding, and anti-corrosion properties were investigated. This research aims to explore the application prospects of BPCs as NSMs in compact shielding design.