Search

CN-122013108-A - LiF target preparation process based on interface diffusion anchoring

CN122013108ACN 122013108 ACN122013108 ACN 122013108ACN-122013108-A

Abstract

The invention discloses a LiF target preparation process based on interface diffusion anchoring, which comprises the steps of preheating a metal substrate to 200-300 ℃, depositing a LiF film on the surface of the substrate through a vacuum evaporation process, and carrying out in-situ annealing to obtain a LiF target with high chemical purity, high surface uniformity and high film base binding force. The invention introduces a substrate preheating process, improves the interdiffusion capability between LiF molecules deposited on the surface of the substrate and metal atoms of the substrate, ensures that the LiF molecules have enough time to carry out mutual dissolution expansion with the metal atoms of the substrate and complete crystallization rearrangement before cooling by integrally optimizing the vacuum evaporation process parameters of the LiF film, thereby forming a firm diffusion anchoring interface structure and obviously enhancing the film base binding force. By introducing an in-situ annealing process, the thermal stress generated between the LiF film layer and the substrate due to mismatch of thermal expansion coefficients is released, and the LiF target is ensured to be not easy to fall off under high-energy proton bombardment.

Inventors

  • CHEN FAGUO
  • ZHANG KE
  • LIU LIYE
  • Qiao Chaopeng
  • LI DEYUAN
  • WANG ZHEN
  • YAN XUEWEN
  • JIA ZHENG

Assignees

  • 中国辐射防护研究院

Dates

Publication Date
20260512
Application Date
20260121

Claims (9)

  1. 1. The preparation process of the LiF target based on interface diffusion anchoring is characterized by comprising the following steps of: S1, vacuum pumping Loading the substrate and the evaporation raw materials into a vacuum chamber, and vacuumizing until the pressure of the chamber is less than or equal to 10 -4 Pa; S2, preheating the substrate Heating the substrate to 200-300 ℃ and keeping the temperature of the substrate constant; S3, evaporation and deposition Preheating evaporation raw materials by adopting a resistance heating method, depositing a LiF film layer on the surface of a substrate after the evaporation rate is stable until reaching a target thickness, closing resistance heating, and ending evaporation deposition; S4, in-situ annealing And (3) in-situ cooling the substrate to room temperature along with the furnace in a vacuum environment to obtain the LiF target.
  2. 2. The process for preparing a LiF target of claim 1, wherein said substrate is a metal Ta, ag, mo, pt, al.
  3. 3. The process for preparing a LiF target according to claim 1, wherein the substrate is ultrasonically cleaned and dried by sequentially using acetone, absolute ethyl alcohol, and deionized water before being loaded into the vacuum chamber.
  4. 4. The LiF target production process according to claim 1, wherein a deposition distance between the substrate and the evaporation source is 20 to 30cm.
  5. 5. The LiF target production process according to claim 1, wherein in step S2, the substrate is heated to 220 ℃.
  6. 6. The process for preparing a LiF target according to claim 1, wherein in step S3, the rotary substrate table is turned on and the substrate is rotated at 5 to 15 rpm.
  7. 7. The LiF target preparation process according to claim 1, wherein in the step S3, the deposition rate of the LiF film layer is 0.1-1 nm/S.
  8. 8. The process for preparing a LiF target according to claim 1, wherein in step S4, the cooling rate of the substrate in-situ cooling with the furnace is 1-5 ℃.
  9. 9. The LiF target preparation process of claim 1, wherein the LiF film layer of the LiF target has a thickness of 100-1200 nm.

Description

LiF target preparation process based on interface diffusion anchoring Technical Field The invention belongs to the technical field of accelerator neutron source target preparation, and particularly relates to a LiF target preparation process based on interface diffusion anchoring. Background In accelerator-based neutron source generation, bombardment of the LiF target (7Li(p,n)7 Be) with protons is the dominant approach to generating monoenergetic neutrons. In the prior art, liF with the thickness of hundreds of nanometers is mainly deposited on a metal substrate by adopting a vacuum evaporation coating or magnetron sputtering technology. Although the vacuum evaporation method can ensure the high chemical purity and the high surface uniformity of the film layer, the film substrate has poor bonding force and is easy to peel off under long-time beam bombardment due to the difference of the thermal expansion coefficients of LiF and Ag and other metal substrates and the lower matching degree of the surface energy. Although the magnetron sputtering method can improve the bonding force, the impurity gas is easy to introduce, so that the unienergy of neutron energy spectrum generated when protons bombard the LiF target is reduced. Therefore, in order to improve the film-based bonding strength of the LiF target and solve the problem of film falling-off of the LiF target due to thermal stress concentration under beam bombardment, it is highly desirable to provide a process for preparing the LiF target with high chemical purity, high surface uniformity and high film-based bonding force. Disclosure of Invention In order to solve the technical problems, the invention provides a LiF target preparation process based on interfacial diffusion anchoring, so that a LiF target with high surface uniformity, high chemical purity and strong film base binding force can be prepared. The invention discloses a LiF target preparation process based on interface diffusion anchoring, which comprises the following steps: S1, vacuum pumping Loading the substrate and the evaporation raw materials into a vacuum chamber, and vacuumizing until the pressure of the chamber is less than or equal to 10 -4 Pa; S2, preheating the substrate Heating the substrate to 200-300 ℃ and keeping the temperature of the substrate constant; S3, evaporation and deposition Preheating evaporation raw materials by adopting a resistance heating method, depositing a LiF film layer on the surface of a substrate after the evaporation rate is stable until reaching a target thickness, closing resistance heating, and ending evaporation deposition; S4, in-situ annealing And (3) in-situ cooling the substrate to room temperature along with the furnace in a vacuum environment to obtain the LiF target. Further, the substrate is a metal Ta, ag, mo, pt, al. Further, before the substrate is placed in the vacuum chamber, the substrate is sequentially cleaned by using acetone, absolute ethyl alcohol and deionized water, and dried. Further, the deposition distance between the substrate and the evaporation source is 20-30 cm. Further, in step S2, the substrate is heated to 220 ℃. Further, in step S3, the rotating substrate table is turned on, and the substrate is rotated at a rotation speed of 5-15 rpm. Further, in step S3, the deposition rate of the LiF film layer is 0.1-1 nm/S. Further, in the step S4, the cooling rate of the substrate in-situ cooling along with the furnace is 1-5 ℃ per minute. Further, the LiF film layer thickness of the LiF target is 100-1200 nm. Compared with the prior art, the preparation process of the LiF target based on interface diffusion anchoring has at least the following outstanding beneficial effects: According to the invention, through optimizing the vacuum evaporation process of the LiF film, particularly through introducing a substrate preheating process and an in-situ annealing process, the diffusion of LiF molecules on the surface of the substrate and the micro-diffusion at the interface are promoted, and on the basis of ensuring that the LiF film has high chemical purity and high surface uniformity, the physical and chemical bonding strength between the film and the substrate is obviously enhanced. Scratch experiments show that the critical load of the film base binding force of the LiF target prepared by the preparation process is about 2N, and the critical load is improved by about 4-5 times compared with that of the LiF target prepared by the substrate-free preheating process, and the LiF target prepared by the preparation process can meet the requirement of generating a stable single-energy neutron radiation field. Drawings In order to more clearly illustrate the technical solution of the embodiments of the present application, the following description will briefly explain the drawings used in the description of the embodiments. It is obvious that the drawings described below are only some embodiments of the present application, and that oth