Method for preparing a simulated sample of marine-exposed wooden cultural relics

Abstract

The present invention relates to a method for preparing a simulated sample of marine waterlogged wooden cultural relics, comprising: 1) After a healthy wood sample block is soaked in an alkali solution under negative pressure, the solution is heated to boiling, and deionized water is continuously added during this period to keep the volume of the solution unchanged; 2) The sample block is transferred to deionized water, heated to boiling, the water is removed at certain time intervals, deionized water is added and heating is continued until the color of the solution no longer changes significantly, the sample block is taken out and dried to a constant weight; 3) The sample block is put into the alkali solution, heated to boiling, and deionized water is continuously added during this period to keep the volume of the solution unchanged; the sample block is taken out and dried to a constant weight; 4) The sample block is immersed in an iron sulfate solution under negative pressure; 5) The sample block is taken out and rinsed with water to remove loose deposits on the surface; 6) The sample block is soaked in an oxidant solution to obtain a simulated sample.

Description

Technical Field

[0001] The present invention belongs to the field of cultural relics protection, and more particularly, relates to a method for preparing a simulated sample of marine-excavated wooden cultural relics. Background Art

[0002] Wood is a natural porous material with the characteristics of inhomogeneity and anisotropy. In the marine environment, due to the erosion of bacteria leading to the decomposition of cellulose, wooden cultural relics will degrade, and the degree of degradation gradually decreases from the outside to the inside. At the same time, due to the porous structure of wood and the presence of iron (from the marine environment and iron cultural relics around the wooden cultural relics) and sulfur, a large amount of iron-rich sediments are usually enriched in the wood structure of marine-excavated wooden cultural relics.

[0003] The wood of marine-excavated wooden cultural relics has the following characteristics: 1) The physical properties of the excavated wooden cultural relics conform to the law that the basic density gradually decreases with the continuous increase of the maximum moisture content; the chemical components show that with the increase of the degradation degree, the content of holocellulose decreases, while the relative content of lignin increases; the ash content in the chemical components is much higher than that of healthy wood; the proportion of Fe element in the ash is the highest, and the content of S element is also relatively high. 2) Reduced iron-rich sediments formed in the marine burial environment, such as FeS, FeS 2 and Fe 3 S 4 etc., are enriched in the microstructure of wooden cultural relics. After the wooden cultural relics are salvaged from the water, FeS, FeS 2 and Fe 3 S 4 etc. are oxidized to form oxidized Fe 2 O 3 , FeOOH and Fe 2 (SO 4 ) 3 and other compounds. A distribution characteristic is formed in which the surface layer of the wood is mainly composed of trivalent iron compounds and the interior of the wood is mainly composed of divalent iron compounds, and this phenomenon is particularly common in marine-excavated wooden cultural relics in China. 3) During the oxidation process of reduced iron-rich sediments, by-products sulfuric acid is generated, making the wooden cultural relics acidic, which further causes the degradation of the wood. The Fenton reaction involving Fe 2+ / Fe 3+ will also lead to the degradation of cellulose. In addition, during the oxidation process of FeS, FeS 2 and Fe 3 S 4 and other compounds, the volume of the generated products increases continuously per molecule, and the loss of water and precipitation will cause stress damage to the microstructure of the wood. 4) Iron-rich sediments not only adhere to the surface of wooden cultural relics, but also penetrate into the microstructure of wooden cultural relics, making the appearance of wooden cultural relics yellow, reddish-brown, red-brown, etc., and a large number of small particles containing iron compounds are enriched in the internal tracheids.

[0004] The scarcity and indestructibility of cultural relics limit the protection research by samples. Therefore, it is very necessary to prepare simulated samples with low holocellulose content and iron-containing sediments like the marine-exposed wooden cultural relics to provide sacrificial samples for the protection research of marine-exposed wooden cultural relics.

[0005] Currently, the methods for preparing simulated samples of marine-exposed wooden cultural relics mainly include: 1) Immersing wood in artificial seawater in the presence of iron; 2) Soaking wood with FeCl 2 solution to deposit Fe 2+ in the wood for studying the influence of Fe 2+ on the wood; 3) Reacting FeCl 2 and Na 2 S solutions in the wood to obtain iron sulfide compounds for studying the influence of iron sulfide compounds on the wood and, on this basis, studying the removal efficiency of sediment removal materials on iron sulfide compounds.

[0006] However, for the simulated samples prepared by the above methods, the wood has not been degraded, and there are differences from marine-exposed wooden cultural relics in terms of the physical properties and chemical components of the wood and the spatial distribution of sediments. Moreover, the seawater immersion method can only form salts composed of water-soluble elements such as Na, K, and Cl in the wood structure, which is quite different from the large amount of insoluble iron-containing sediments in marine-exposed wooden cultural relics.

[0007] In addition, the iron sulfide compounds formed in the marine environment are enriched in the wood structure. After the wooden cultural relics are salvaged from the water, continuous oxidation reactions occur, forming complex iron-containing sediments containing divalent iron compounds and trivalent iron compounds. Therefore, in the process of simulating the sediment enrichment process, only using Fe 2+ or Fe 2 S to form iron sulfide compounds results in a single component, which does not conform to the actual situation of most existing marine-exposed wooden cultural relics and is likely to cause deviations in the protection research of marine-exposed wooden cultural relics.

[0008] Aiming at the shortcomings of the existing technology, the present invention provides a method for preparing a simulated sample of marine-exposed wooden cultural relics, obtaining a simulated wood sample that is consistent with marine-exposed wooden cultural relics in terms of wood degradation characteristics, sediment components, and distribution patterns, which can be used as a sacrificial sample for the protection research of marine-exposed wooden cultural relics very well. Summary of the Invention

[0009] The present invention provides a method for preparing a simulated sample of marine-exposed wooden cultural relics, in which healthy wood is boiled in a boiling alkali solution for a period of time to degrade the wood; then FeSO 4 solution is infiltrated under negative pressure so that FeSO4 Fully penetrate into the interior of the wood; then soak it in an oxidant solution to oxidize some of the deposits in the wood, forming a surface layer mainly composed of trivalent iron compounds Fe 2 O 3 , FeOOH, Fe 2 (SO 4 ) 3 etc. as the main deposits, and a simulated wood sample with divalent iron compounds such as FeSO 4 etc. as the main deposits inside.

[0010] A method for preparing a simulated sample of marine-exposed wooden cultural relics, comprising the following steps:

[0011] 1) Immerse a healthy wood block in an alkali solution under negative pressure for a certain period of time to accelerate the penetration of the alkali solution into the wood; then heat the alkali solution to boiling and continue for a certain period of time to degrade the wood; continuously add deionized water during the heating process to keep the volume of the alkali solution constant;

[0012] 2) Take out the wood block from step 1), transfer it to an appropriate amount of deionized water, heat the water to boiling and continue for a period of time to remove the degradation products and residual alkali in the wood; remove the water at certain time intervals, add deionized water and continue heating to increase the moisture content of the wood until the color of the solution no longer changes significantly, then take out the wood block and dry it to a constant weight;

[0013] 3) Put the wood block obtained in step 2) into an alkali solution, heat the alkali solution to boiling and continue for a certain period of time; continuously add deionized water during the heating process to keep the volume of the alkali solution constant; then take out the wood block and dry it to a constant weight;

[0014] 4) Place the wood block obtained in step 3) in a solution of iron sulfate and soak it under negative pressure for a certain period of time;

[0015] 5) Take out the wood block from step 4) and rinse it with water to remove the loose deposits attached to its surface;

[0016] 6) Soak the wood block obtained in step 5) in a solution of an oxidant to obtain a simulated sample of marine-exposed wooden cultural relics.

[0017] Among them, in step 1), the alkali solution can be an NaOH solution and / or a KOH solution, preferably an NaOH solution. The concentration of the alkali solution is 0.5 - 1.5 mol / L. The mass-to-volume ratio (g / ml) of the wood mass used to the volume of the alkali solution is 1:20 to 1:40. The negative pressure is a vacuum of 500 - 800 mbars, preferably 600 - 700 mbars; the negative pressure soaking time is 7 - 10 h. The size of the wood sample block is not particularly limited, usually for example 1*0.5*0.1 cm 3 -3*3*3 cm 3 . The heating time is 6 - 30 h, preferably 6 - 18 h.

[0018] In step 2), the continuous heating time is 5 - 9 h, the interval time for replacing deionized water is about 30 min, and the removed water contains wood degradation products dissolved therein and residual alkali. The drying is vacuum freeze-drying, supercritical drying or drying in an oven, preferably vacuum freeze-drying.

[0019] In step 3), the alkali solution used can be the same as or different from the alkali solution in step 1), preferably the same, and its concentration is 0.5 - 1 mol / L. The mass-to-volume ratio (g / ml) of the wood mass used to the volume of the alkali solution is 1:20 to 1:40. The continuous heating time is 3 - 6 h. The drying is vacuum freeze-drying, supercritical drying or drying in an oven, preferably vacuum freeze-drying.

[0020] The further alkali solution treatment in step 3) has two functions. One is to continue to degrade the wood so that the physical properties and chemical components of the wood are more in line with the characteristics of marine-excavated wooden cultural relics; the other is that the alkali retained in the wood can react with the iron sulfate solution in the next step.

[0021] In step 4), the iron sulfate can be FeSO 4 , for example FeSO 4 ﹒7H 2 O or FeSO 4 ﹒H 2 O. The concentration of the iron sulfate solution is about 0.5 mol / L - 1.5 mol / L. The mass-to-volume ratio (g / ml) of the wood mass used to the volume of the solution is 1:10 to 1:40. The negative pressure is a vacuum of 500 - 800 mbars, preferably 600 - 700 mbars. The soaking time under negative pressure is 5 - 8 h.

[0022] In step 6), the oxidant can be, but is not limited to, for example H 2 O 2, NaClO, and chloramine-T. The concentration of the solution is 1 - 3 mol / L, and the mass-to-volume ratio (g / ml) of the wood mass used to the solution volume is 1:20 to 1:40; the soaking time is 3 - 5 h.

[0023] For the enrichment ratio of the sediment in the obtained simulated sample, the calculation is carried out as follows:

[0024] After the treatment in step 3), the sample block is dried and weighed, and the mass is marked as m 1 ; after the treatment in step 6), the sample block is dried and weighed, and the mass is marked as m 2 , then the mass of the sediment in the wood is m 2 - m 1 , and the enrichment ratio of the sediment in the wood is (100 * (m 2 - m 1 ) / m 2 )%.

[0025] The method of the present invention is applicable to any wood species, including but not limited to, for example, pine, fir, camphor wood, etc.

[0026] The advantages of the method of the present invention are as follows: 1) The wood treated with the alkali solution is consistent with the characteristics of the marine-exposed wooden cultural relics in terms of physical properties (such as the maximum moisture content and basic density) and chemical components, that is, the physical properties conform to the law that as the maximum moisture content of the marine-exposed wooden cultural relics increases, the basic density gradually decreases, and the chemical components of the wood matrix conform to the characteristics that as the degradation degree of the marine-exposed wooden cultural relics increases, the content of holocellulose decreases and the relative content of lignin gradually increases. 2) The marine-exposed wooden cultural relics are enriched with sediments and have a high ash content, which contains a large amount of Fe and S, which is one of the important characteristics of the marine-exposed wooden cultural relics. In the simulated wood sample obtained by the method of the present invention, the enriched sediment is iron oxide and iron sulfate, and the chemical components of the sediment are more in line with the characteristics of the marine-exposed wooden cultural relics. 3) After the wood is soaked in the FeSO4 solution and then oxidized with the H 2 O 2 solution, the formed iron-containing sediment enriches from the surface to the inside along the wood tracheids, mainly enriching in the lumen and cell wall of the wood tracheids. The components of the sediment are FeOOH, Fe 2 (SO 4 ), Fe 2 O 3, making the phase of iron deposits in the simulated samples of the present invention and their spatial distribution in wood more in line with the characteristics of marine-excavated wooden cultural relics. 4) The present invention optimizes the process conditions and gives the optimized conditions for preparing simulated samples of marine-excavated wooden cultural relics, which can not only obtain simulated samples with the same appearance, morphology, components, and microscopic morphology as typical marine-excavated wooden cultural relics, but also save energy and reduce the pollution caused by excessive use of chemical reagents. 5) The method of the present invention has simple, safe, high-efficiency, and good repeatability processes, and can provide a large number of sacrificial samples as needed for research work on desalination, reinforcement, sealing, dehydration and shaping, and preventive protection of marine-excavated wooden cultural relics, avoiding damage to the cultural relics themselves during the protection research process, and having very important practical significance. Description of the Drawings

[0027] Figure 1A Ultra-depth-of-field microscope photograph of the transverse surface of the pine simulated sample prepared in Example 1.

[0028] Figure 1B Ultra-depth-of-field microscope photograph of the longitudinal surface of the pine simulated sample prepared in Example 1.

[0029] Figure 2A Optical microscope photograph of the transverse section of a typical marine-excavated wooden cultural relic sample enriched with iron deposits.

[0030] Figure 2B Optical microscope photograph of the longitudinal section of a typical marine-excavated wooden cultural relic sample enriched with iron deposits.

[0031] Figure 3A Optical microscope photograph of the transverse section of the pine simulated sample prepared in Example 1.

[0032] Figure 3B Optical microscope photograph of the longitudinal section of the pine simulated sample prepared in Example 1.

[0033] Figure 4 X-ray diffraction analysis pattern of a typical marine-excavated wooden cultural relic sample.

[0034] Figure 5 X-ray diffraction analysis patterns of iron deposits in the pine simulated sample prepared in Example 1 and the fir simulated sample prepared in Example 7.

[0035] Figure 6 Box plot of the enrichment ratio of sediments in the wood simulated samples prepared in Example 1, Example 6, Example 7, Comparative Example 1, Comparative Example 2, and Comparative Example 3; in the figure, □ represents the average value of the iron deposit content; ◆ represents the outlier of the iron deposit content; — represents the median of the iron deposit content; the box represents the interval where 25% to 75% of the iron deposit content data is located.

[0036] Figure 7 For the variation rules of the maximum moisture content and basic density of the pine samples in Examples 1 to 5 with the increase of the heating time in Step 1.

[0037] Figure 8 For the comparison of the infrared spectra of the pine samples obtained in Step 1 in Examples 1 to 5 with the infrared spectrum of fresh pine.

[0038] Figure 9A For the ultra-depth-of-field microscope photos of the transverse surface of the Chinese fir simulated samples prepared in Example 7.

[0039] Figure 9B For the ultra-depth-of-field microscope photos of the longitudinal surface of the Chinese fir simulated samples prepared in Example 7.

[0040] Figure 10 For the variation rules of the maximum moisture content and basic density of the Chinese fir samples in Examples 7 to 11 with the increase of the heating time in Step 1.

[0041] Figure 11A For the ultra-depth-of-field microscope photos of the transverse surface of the pine simulated samples prepared in Comparative Example 1. It can be seen that black deposits adhere to the sample surface, which does not conform to the appearance characteristics of marine-excavated wooden cultural relics.

[0042] Figure 11B For the ultra-depth-of-field microscope photos of the longitudinal surface of the pine simulated samples prepared in Comparative Example 1. It can be seen that black deposits adhere to the sample surface, which does not conform to the appearance characteristics of marine-excavated wooden cultural relics.

[0043] Figure 12A For the ultra-depth-of-field microscope photos of the transverse surface of the pine simulated samples obtained in Comparative Example 2. It can be seen that black deposits adhere to the sample surface, which does not conform to the appearance characteristics of marine-excavated wooden cultural relics.

[0044] Figure 12B For the ultra-depth-of-field microscope photos of the longitudinal surface of the pine simulated samples obtained in Comparative Example 2. It can be seen that black deposits adhere to the sample surface, which does not conform to the appearance characteristics of marine-excavated wooden cultural relics. Specific implementation examples

[0045] The present invention will be further explained in detail below with reference to specific examples, but the present invention is not limited thereto. The samples and reagents used in the examples of the present invention are all commercially available.

[0046] Example 1

[0047] 1) Take several pieces with a total mass of about 15 g and dimensions of 1*1*1 cm 3Put the healthy pine wood into 450 ml of NaOH solution with a concentration of 1 mol / L, soak it under a negative pressure of 600 mbars for 8 h, and then heat the solution to boiling and continue for 6 h; continuously add deionized water during the heating process to keep the solution volume unchanged;

[0048] 2) Take out the pine wood sample block, transfer it to deionized water, heat the water to boiling and continue for a certain period of time; during the heating process, remove the solution therein every about 30 min, add deionized water and continue heating. When heating for more than 5 h, after replacing the deionized water, the color of the solution no longer changes significantly, indicating that the degradation products and the removal of alkali slow down; continue heating for a total of about 9 h; then take out the pine wood sample block and vacuum freeze-dry it to constant weight;

[0049] 3) Put the pine wood sample block treated by the above steps into 450 ml of NaOH solution with a concentration of 0.5 mol / L, heat the solution to boiling and continue for 4 h, then take it out and vacuum freeze-dry it to constant weight;

[0050] 4) Under a vacuum of 600 mbars, soak the pine wood sample block from step 3) in 150 ml of FeSO 4 ·7H 2 O solution for 6 h;

[0051] 5) Take out the sample block and rinse it with a large amount of water until the loose sediment attached to its surface falls off;

[0052] 6) Immerse it in 300 ml of H 2 O 2 solution with a concentration of 3 mol / L for 4 h to obtain a simulated sample.

[0053] Figure 1A and 1B are respectively the ultra-depth-of-field microscope photos of the transverse surface and the longitudinal surface of the pine wood simulated sample prepared in Example 1. From Figure 1A 、 1B It can be seen that iron-containing sediments are attached to the surface of the obtained pine wood sample, showing a reddish-brown color, which is different from the light yellow color of healthy pine wood and is consistent with the reddish-brown color presented on the surface of marine waterlogged wooden cultural relics enriched with iron-containing sediments commonly seen, indicating that the obtained simulated sample has the appearance characteristics consistent with those of marine waterlogged wooden cultural relics enriched with iron-containing sediments.

[0054] Figure 2A and 2BOptical micrographs of the transverse and longitudinal sections of a typical marine-excavated wooden cultural relic sample enriched with iron-bearing sediments, showing the microscopic characteristics of the typical marine-excavated wooden cultural relic sample enriched with iron-bearing sediments. In the transverse section, granular iron-bearing sediments can be seen mainly adhering to the lumens of the wood tracheids (indicated by the arrows in the figure), and the particles are reddish-brown; in the longitudinal section, it can be seen that the iron-bearing sediments have filled the wood tracheids to a certain extent (indicated by the circles in the figure), indicating the presence of iron-bearing sediments inside the wood.

[0055] Figure 3A and 3B Optical microscope observation images of the transverse and longitudinal sections of the pine wood simulated sample prepared in Example 1. From the micrographs of the transverse section, it can be seen that the iron-bearing sediments in the obtained pine wood simulated sample are mainly enriched in the lumens of the wood tracheids (indicated by the arrows in the figure), and the particles are reddish-brown; in the longitudinal section, it can be seen that the reddish-brown iron-bearing sediments have filled the tracheids to a certain extent (indicated by the circles in the figure), indicating that iron-bearing sediments have also formed inside the simulated sample. Comparing Figure 2A , 2B and Figure 3A , 3B it can be seen that the microscopic morphology of the simulated sample obtained in Example 1 is consistent with the microscopic morphology characteristics of marine-excavated wooden cultural relics.

[0056] Figure 4 is the X-ray diffraction analysis pattern of a typical marine-excavated wooden cultural relic sample, showing the phase characteristics of the iron-bearing sediments in the marine-excavated wooden cultural relic sample, mainly including FeOOH, Fe 2 (SO 4 ) 3 and Fe 2 O 3 .

[0057] Figure 5 From the X-ray diffraction analysis pattern of the pine wood simulated sample prepared in Example 1 in 2 (SO 4 ) 3 it can be seen that the phases of the sediments in the pine wood simulated sample include FeOOH, Fe 2 O 3 . Comparing with Figure 4 it can be seen that the pine wood simulated sample obtained in Example 1 conforms to the phase characteristics of the iron-bearing sediments in marine-excavated wooden cultural relics.

[0058] Figure 6 Based on the data given in

[0059] Example 2:

[0060] Repeat Example 1, except that the boiling time of the solution in step 1) is 12 h, and the concentration of the sodium hydroxide solution in step 3) is 1 mol / L.

[0061] The appearance characteristics and microscopic morphology of the simulated sample obtained in Example 2 are similar to the results obtained in Example 1, and the sediment enrichment ratio is 6.67%-22.01% of the wood mass.

[0062] Example 3:

[0063] Repeat Example 1, except that the boiling time of the solution in step 1) is 18 h, and the heating time in step 3) is 6 h.

[0064] The appearance characteristics and microscopic morphology of the simulated sample obtained in Example 3 are similar to the results obtained in Example 1, and the sediment enrichment ratio is 7.55%-24.32% of the wood mass.

[0065] Example 4:

[0066] Repeat Example 1, except that the boiling time of the solution in step 1) is 24 h, and the soaking time in step 4) is 5 hours.

[0067] The appearance characteristics and microscopic morphology of the simulated sample obtained in Example 4 are similar to the results obtained in Example 1, and the sediment enrichment ratio is 6.71%-24.88% of the wood mass.

[0068] Example 5:

[0069] Repeat Example 1, except that the boiling time of the solution in step 1) is 30 h, and the soaking time in step 4) is 8 hours.

[0070] The appearance characteristics and microscopic morphology of the simulated sample obtained in Example 5 are similar to the results obtained in Example 1, and the sediment enrichment ratio is 8.11%-29.98% of the wood mass.

[0071] Figure 7 Shows the variation laws of the maximum moisture content and basic density of the pine wood samples in Examples 1 to 5 with the increase of the heating time in step 1. It can be seen that with the increase of the heating time, the maximum moisture content of the pine wood samples increases, and the basic density decreases, and its variation law is consistent with the physical property variation law of the marine-exposed wooden cultural relics. When the heating time is greater than 6 h, the variation trends of the maximum moisture content and basic density of the pine wood slow down, and based on this, the alkali solution heating process can be ended.

[0072] Figure 8Shown is the comparison of the infrared spectra of the pine wood samples obtained in Step 1 of Examples 1 to 5 with the infrared spectrum of fresh pine wood. It can be seen that after heating in the alkali solution for 6 h, the characteristic band at 1737 cm -1 disappears, indicating that most of the hemicellulose and fatty acid extracts in the pine wood are excluded or migrated. As the heating time increases, with the intensity normalization of the lignin characteristic band at 1510 cm -1 in the infrared spectrum, the intensity of the cellulose characteristic band at 1371 cm -1 decreases continuously, indicating that the relative content of holocellulose in the wood gradually decreases after treatment with the NaOH solution. This trend conforms to the variation law that the relative content of holocellulose in the chemical components of marine-exposed wood decreases with the increase in the degree of degradation.

[0073] Example 6:

[0074] Repeat Example 1, except that in Step 4), the concentration of the FeSO 4 ·7H 2 O solution is 1 mol / L.

[0075] The appearance characteristics and microscopic morphology of the simulated sample obtained in Example 6 are similar to those obtained in Example 1. From the Figure 6 data given, the sediment enrichment ratio is 13.58% - 23.45% of the wood mass.

[0076] Example 7:

[0077] Repeat Example 1, except that healthy Chinese fir is used instead of healthy pine wood; in Step 1), the concentration of the NaOH solution is 1.5 mol / L and the volume is 600 ml.

[0078] Figure 9A and 9B are the ultra-depth-of-field microscope photos of the transverse surface and longitudinal surface of the Chinese fir simulated sample prepared in Example 7, respectively. It can be seen that the surface of the obtained Chinese fir sample is attached with iron-containing sediments and presents a reddish-brown color, which is different from the light yellow color of healthy Chinese fir and is consistent with the reddish-brown color presented on the surface of marine-exposed wooden cultural relics enriched with iron-containing sediments usually seen, indicating that the obtained simulated sample has the appearance characteristics consistent with those of marine-exposed wooden cultural relics enriched with iron-containing sediments.

[0079] Figure 4 is the X-ray diffraction analysis pattern of a typical marine-exposed wooden cultural relic sample, showing the phase characteristics of the iron-containing sediments in the marine-exposed wooden cultural relic sample, mainly including FeOOH, Fe 2 (SO 4 ) 3 and Fe 2 O 3 .

[0080] From Figure 5 the X-ray diffraction pattern of the Chinese fir simulated sample prepared in Example 7, it can be seen that the phases of the deposits in the Chinese fir simulated sample obtained in Example 7 include FeOOH, Fe 2 (SO 4 ) 3 and Fe 2 O 3 . Compared with Figure 4 , it can be known that the Chinese fir simulated sample obtained in Example 7 conforms to the phase characteristics of the iron deposits in the marine-exposed wooden cultural relics.

[0081] From Figure 6 the data given, it can be known that the enrichment ratio of the deposits in the Chinese fir simulated sample of Example 7 is 10.86%-22.49% of the wood mass.

[0082] Example 8:

[0083] Repeat Example 7, except that the boiling time of the solution in step 1) is 12 h and the concentration of the sodium hydroxide solution in step 3) is 1 mol / L.

[0084] The appearance characteristics and microscopic morphology of the simulated sample obtained in Example 8 are similar to those obtained in Example 7, and the enrichment ratio of the deposits is 11.42%-23.46% of the wood mass.

[0085] Example 9:

[0086] Repeat Example 7, except that the boiling time of the solution in step 1) is 18 h and the heating time in step 3) is 5 h.

[0087] The appearance characteristics and microscopic morphology of the simulated sample obtained in Example 9 are similar to those obtained in Example 7, and the enrichment ratio of the deposits is 11.91%-26.32% of the wood mass.

[0088] Example 10:

[0089] Repeat Example 7, except that the boiling time of the solution in step 1) is 24 h and the soaking time in step 4) is 8 hours.

[0090] The appearance characteristics and microscopic morphology of the simulated sample obtained in Example 10 are similar to those obtained in Example 7, and the enrichment ratio of the deposits is 12.03%-26.67% of the wood mass.

[0091] Example 11:

[0092] Repeat Example 7, except that the boiling time of the solution in step 1) is 30 h, the soaking time in step 4) is 8 h, and the volume of the soaking solution is 600 ml.

[0093] The appearance characteristics and microscopic morphology of the simulated samples obtained in Example 11 are similar to those obtained in Example 7, and the enrichment ratio of the sediment is 18.35%-30.17% of the wood quality.

[0094] Figure 10 It shows the variation rules of the maximum moisture content and basic density of the Chinese fir samples in Examples 7 to 11 with the increase of the heating time in Step 1. It can be seen that with the increase of the heating time, the maximum moisture content of the Chinese fir samples increases and the basic density decreases, and its variation rule is consistent with the physical property variation rule of the marine-exposed wooden cultural relics. When the heating time is greater than 6 h, the variation trends of the maximum moisture content and basic density of Chinese fir slow down. Based on this, the alkali solution heating process can be ended.

[0095] Comparative Example 1:

[0096] Repeat Example 1, except that only Steps 1), 2), 3), 4) and 5) of the method of the present invention are implemented, that is: the step of soaking the wood sample block with the oxidant solution is not carried out.

[0097] Figure 11A and 11B are the ultra-depth-of-field microscope photos of the transverse surface and longitudinal surface of the pine simulated sample prepared in Comparative Example 1. It can be seen that the sediment on the surface of the obtained wood sample is black, which does not conform to the appearance characteristics of the marine-exposed wooden cultural relics enriched with iron deposits.

[0098] Comparative Example 2:

[0099] Repeat Example 1, except that only Steps 1), 2) and 4) are implemented.

[0100] Figure 12A and 12B are the ultra-depth-of-field microscope photos of the transverse surface and longitudinal surface of the pine simulated sample obtained in Comparative Example 2. It can be seen that the sediment on the surface of the obtained wood sample is black, which does not conform to the appearance characteristics of the marine-exposed wooden cultural relics enriched with iron deposits.

[0101] Comparative Example 3:

[0102] Repeat Example 1, except that in Step 3), the concentration of the NaOH solution is 1.5 mol / L.

[0103] Detection shows that the pH of the obtained wood soaking solution is 7-9, showing alkalinity, which does not conform to the acidic characteristics of the marine-exposed wooden cultural relics enriched with iron deposits.

Claims

1. A method for preparing a simulated sample of marine-excavated wooden cultural relics, comprising the following steps: 1) Immerse healthy wood blocks in an alkali solution under negative pressure for a certain period of time, then heat the alkali solution to boiling and continue heating for 6 - 30 h; continuously add deionized water during the heating process to keep the volume of the alkali solution unchanged; 2) Take out the wood blocks from step 1), transfer them to deionized water, heat to boiling and continue heating for 5 - 9 h; remove the water therein at certain time intervals during this period, then add deionized water and continue heating until the color of the solution no longer changes significantly, then take out the wood blocks and dry them to a constant weight; 3) Put the wood blocks obtained in step 2) into an alkali solution, heat the alkali solution to boiling and continue heating for 3 - 6 h; continuously add deionized water during the heating process to keep the volume of the alkali solution unchanged; then take out the wood blocks and dry them to a constant weight; the concentration of the alkali solution is 0.5 - 1 mol / L; 4) Place the wood blocks obtained in step 3) in a solution of ferrous sulfate, and immerse them under negative pressure for 5 - 8 h; 5) Take out the wood blocks from step 4), and rinse them with water to remove the loose sediments attached to their surfaces; 6) Immerse the wood blocks obtained in step 5) in a solution of an oxidant for 3 - 5 h to obtain a simulated sample of marine-excavated wooden cultural relics.

2. The method according to claim 1, wherein in step 1), the alkali solution is an NaOH solution and / or a KOH solution; the concentration of the alkali solution is 0.5 - 1.5 mol / L, and the mass-to-volume ratio (g / ml) of the wood quality used to the volume of the alkali solution is 1:20 to 1:

40.

3. The method according to claim 1, wherein in step 1), the negative pressure is a vacuum of 500 - 800 mbars.

4. The method according to claim 1, wherein in step 2), the interval for replacing deionized water is 30 min, and the drying is vacuum freeze-drying, supercritical drying or oven drying.

5. The method according to claim 1, wherein in step 3), the alkali solution used is the same as or different from the alkali solution in step 1, and the mass-to-volume ratio (g / ml) of the wood quality used to the volume of the alkali solution is 1:20 to 1:

40.

6. The method according to claim 1, wherein in step 3), the drying is vacuum freeze-drying, supercritical drying or oven drying.

7. According to the method described in claim 1, in step 4), the iron sulfate is FeSO 4 ; the concentration of the iron sulfate solution is 0.5 mol / L - 1.5 mol / L, and the mass-to-volume ratio (g / ml) of the wood mass used to the solution volume is 1:10 to 1:

40.

8. The method according to claim 7, wherein the iron sulfate is FeSO 4 ﹒7H 2 O or FeSO 4 ﹒H 2 O.

9. The method according to claim 1, wherein in step 4), the negative pressure is a vacuum of 500 - 800 mbars.

10. According to the method described in claim 1, in step 6), the oxidant is H 2 O 2 , NaClO and chloramine-T; the solution concentration is 1-3 mol / L, and the mass-volume ratio (g / ml) of the mass of the wood used to the volume of the solution is 1:20 to 1:40.

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