Objective  The objective of this study is to investigate the effects of different post-treatment methods on the decay resistance of nano wood preservative impregnated wood, the compression parallel to grain and the leaching resistance of copper ions, aiming to provide the basis for the application of nano-preservatives.

  Method  The nano-CuO/silica sol formulations were prepared by mechanical co-blending, combined with ICP-OES and SEM to investigate the changes of different post-treatment methods（steaming at 100 ℃ and freezing at −30 ℃）on the decay resistance of impregnated wood, compression parallel to grain, impregnated wood preservative distribution and copper ion leaching resistance.

  Result  The decay resistance of the specimens impregnated with nano-CuO/silica sol formulations was significantly improved, reaching the standard of “very durable”. The compression parallel to grain increased by 24.42% compared with the untreated material. Compared with the impregnated specimens, the extended steaming post-treatment time resulted in a more uniform and dense distribution of the formulations in the treated material, while the freezing post-treatment resulted in a granular distribution of the formulations. The mass loss of impregnated material after steaming post-treatment for 90 min and freezing post-treatment for 8h was reduced by 18.30% and 24.37%, respectively compared with the impregnated material. Steaming post-treatment for a shorter period of time can improve the leaching resistance of copper ions in impregnated materials, while the leaching resistance of copper ions in impregnated materials after different time of freezing post-treatment was better than that of impregnated materials, and the leaching of copper ions was reduced by 8.72%−34.40%. Compression parallel to grain of steaming post-treated impregnated material was higher than that of normal impregnated specimens, with an increase of 0.64%−5.31%, while the compressive strength of freezing post-treated impregnated material was slightly lower than that of impregnated material.

  Conclusion  Steaming post-treatment was found to be very effective in improving the compression parallel to grain of the impregnated materials with nano-CuO/silica sol preservatives, while freezing post-treatment was more effective in improving the leaching resistance of copper ions. The experimental results provide a reference for the application of different treatments in the selection of nanopreservatives.