38 results about "Picric acid" patented technology

The invention relates to a corrosive agent and a corrosion method for displaying a 32CrNi3MoVE crystal boundary of alloy steel, which are characterized in that a common chemical product is used as an electrolytic corrosive agent after being simply proportioned, and the 32CrNi3MoVE steel quenched and tempered state original austenite crystal boundary is clearly displayed by a proper corrosion method. Chemical reagents used by the corrosive are economical and applicable, the corrosive is composed of alum, oxalic acid, dishwashing liquid, distilled water and the like which are existing in a laboratory, the proportioning of the corrosive is the key, the electrolytic corrosion method is simple to operate, alum can effectively display the grain boundary, oxalic acid provides a weak acid environment for oxidation reduction, and the corrosion effect is good. The dishwashing liquid slows down the corrosion rate of weak acid electrolyte to a metallographic specimen, weakens structure display, and improves the definition of crystal boundary display. The corroded sample is lightly polished in a polishing machine, and the corrosive agent ratio and the electrolytic corrosion method are combined to form an efficient novel corrosion method. The traditional corrosive agent capable of completely replacing saturated picric acid and a proper amount of detergent and the corrosion method effectively solve the problem of 32CrNi 3MoVE steel quenched and tempered state original austenite grain boundary display.

The invention relates to the technical field of pharmaceutical analysis, in particular to a method for detecting the content of guanidine nitrate by precolumn derivatization-high performance liquid chromatography, which comprises the following steps: oscillating and uniformly mixing a guanidine nitrate reference substance or sample and pure water at room temperature, adding sulfuric acid concentrated liquor in cold water bath to perform derivatization reaction, after the reaction is finished, placing at room temperature, and performing column chromatography to obtain the guanidine nitrate content. Adding liquid caustic soda for neutralization, carrying out gradient constant volume by using a mobile phase, and filtering by using a microporous filter membrane to respectively obtain a derivatization reference solution and a derivatization sample solution; and respectively injecting the derivatization reference substance solution and the derivatization sample solution into HPLC, recording peak areas, and calculating the content of guanidine nitrate in the sample by adopting an external standard method. The guanidine nitrate sample is pretreated through the precolumn derivatization reaction, the guanidine nitrate derivative generated through the reaction has the advantages of being high in stability and easy to separate, ammonium nitrate and nitric acid impurities can be effectively prevented from interfering the detection result, the explosive picric acid is not adopted in the detection method, and the detection method is simple, safe and easy to implement.

The invention discloses a composite propellant containing a high-nitrogen ferrocene derivative and a preparation method of the composite propellant. The composite propellant is prepared from the following components: 14.05% of hydroxyl-terminated polybutadiene (HTPB), 7.03% of diisooctyl sebacate (DOS), 0.92% of 2, 4-toluene diisocyanate (TDI), 1% of the high-nitrogen ferrocene derivative, 59% of ammonium perchlorate (AP) and 18.00% of aluminum powder (Al). N, N-dimethylaminomethylferrocene in the three high-nitrogen ferrocene derivatives has the effects of improving the burning rate of the composite propellant and reducing the pressure index as the ferrocene derivative, nitrate, picric acid, 3-nitro-1, 2, 4-triazole-5-ketone and the like are rich in C, H, O and N elements, and are similar to oxidizing agents such as typical components ammonium nitrate, HMD and the like in the composite propellant; the fuel can be decomposed to provide energy for propellant combustion; the propellant has a low combustion rate pressure index in a pressure range of 1-10 MPa, and has more excellent combustion stability.

The invention relates to the technical field of steel and iron material performance detection, in particular to a corrosion method for displaying the original austenite grain boundary of martensitic steel, a corrosion solution does not contain picric acid, a nitric acid alcohol solution and an aqua regia solution, the danger is low, raw materials are easy to obtain, the corrosion process is easy to operate, and the efficiency is high. The original austenite grain boundary of the martensitic steel can be clearly displayed without using electrochemical corrosion complex equipment; a mixed solution of hydrofluoric acid and hydrogen peroxide is selected as a corrosive agent for the austenite grain boundary of the martensitic steel, the corrosivity of the corrosive agent is just matched with the corrosion resistance of the grain boundary of the martensitic steel with medium and low carbon and the Cr content smaller than or equal to 15 wt%, the corrosive agent has sensitivity to the grain boundary, the grain boundary can be clearly displayed, the corrosive agent is not sensitive to an intragranular martensitic structure, and the good inhibition effect is achieved; therefore, a perfect austenite grain boundary display effect is obtained.

The invention relates to the technical field of Stefan acid purification, in particular to a method for purifying Stefan acid from a dinitrobenzene nitration byproduct mixture, which comprises the following steps: S1, dissolving the dinitrobenzene nitration byproduct mixture in water, adjusting the pH value to be alkaline, and filtering to obtain filtrate and filter residue dinitrobenzene solid; s2, adding the filtrate into an organic solvent, extracting, separating liquid, and retaining a water phase; and S3, adjusting the pH value of the water phase to be acidic, heating for acid precipitation, and then cooling for crystallization to obtain a mixed crystal of Stefan acid and picric acid. And S4, heating and mixing the mixed crystal and toluene, and filtering to obtain the high-purity Stefan acid. According to the method, efficient separation is realized through a two-step core process of'alkali dissolution-acidification 'and'selective dissolution'. In the final product, the content of dinitrobenzene can be reduced to 0%, the content of picric acid can be reduced to 1% or below, and the purity of Stefan acid can reach 99% or above.

The application discloses an electrolyte additive, a preparation method thereof, an electrolyte and a lithium ion battery. The preparation method of the electrolyte additive comprises the following steps: dissolving picric acid in an organic solution to obtain an additive solution, wherein the organic solution contains at least one element selected from B, F and N; and crystallizing and precipitating the electrolyte additive from the additive solution. The electrolyte additive is beneficial to making the polymerization layer and SEI film harder and more stable, and is beneficial to inhibiting the growth of lithium dendrites. The electrolyte added with the electrolyte additive can generate an electro-polymerization reaction in the process of battery charging and discharging, thereby reducing the loss of the electrolyte and lithium metal, reducing the resistance of the lithium ion battery and improving the cycle performance of the lithium ion battery. The lithium ion battery provided by the application contains the electrolyte added with the electrolyte additive, and thus has lower resistance and better cycle performance.

The invention relates to a preparation method and application of a fluoroboron dipyrrolidine probe molecule based on a fluorescence lightening mechanism, according to the method, amino in aminophenyl on the 8 site of a fluorescence probe is used as a recognition group, a benzene ring is used as a connector to form a typical photoinduced electron transfer process structure, nitrogen atoms on the amino react with picric acid, and the fluorescence lightening mechanism of the fluorescence probe is obtained. The electron cloud density of probe molecules is changed, the PET process is inhibited, and fluorescence is enhanced; a good linear relation is shown in a certain range, and the explosive picric acid is quantitatively detected based on the linear relation. The method has the advantages of mild reaction conditions, simple test process, good selectivity and high sensitivity, and has good application in the fluorescent sensing aspect of picric acid detection. Therefore, high-sensitivity, quick-response and selective detection of picric acid is realized. The fluorescent probe not only can provide real-time and on-site detection capability, but also can reduce sample pretreatment steps, reduce the detection cost and improve the detection efficiency, thereby better meeting the requirements of practical application.

The application relates to the technical field of metal material detection, and provides an alloy spring steel austenite grain size detection method, which comprises the following steps: carrying out heating and heat preservation treatment on an alloy spring steel sample, the temperature of the heating and heat preservation treatment is in a grain boundary segregation sensitization temperature interval of phosphorus elements, so that the phosphorus elements are segregated at original austenite grain boundaries; carrying out metallographic sampling on the alloy spring steel sample after the heating and heat preservation treatment to obtain a metallographic sample; carrying out corrosion treatment on the metallographic sample under heating conditions by using a water-based etching liquid, the water-based etching liquid comprises picric acid and a surfactant; and observing the metallographic sample after the corrosion treatment to obtain austenite grain size. The application simplifies a detection process, clearly shows original austenite grain boundaries, and improves grading accuracy.

The invention discloses a rapid fixing solution for ink staining of pathological specimens and a preparation method and an application method thereof, which comprises the following components by weight: 100 to 200 parts of glacial acetic acid, 200 to 400 parts of ethanol, 200 to 400 parts of methanol, 50 to 200 parts of tert-amyl alcohol, and 50 to 200 parts of formalin. The rapid fixing solution for ink staining of the invention can stain specimens rapidly and has a good staining effect, and the fixing solution of the invention does not need to use picric acid which is explosive and toxic.

The invention relates to the technical field of tissue section staining, in particular to a multicolor composite staining kit, a staining method and application of the multicolor composite staining kit. The multi-color composite staining kit provided by the invention not only can realize a better staining effect and has high discrimination on staining of different tissue structures, but also does not contain dangerous chemical components such as picric acid, ethanol, ammonia and the like, so that related risks and costs are greatly reduced in the processes of production, storage, transportation, use and discarding; in addition, by adopting the kit disclosed by the invention, the operation steps can be effectively simplified, the operation difficulty is reduced, the repeatability of a dyeing result is remarkably improved, meanwhile, the kit is more friendly to the environment and operators, the cost is lower, and the kit has a better application prospect.

A method for predicting the austenite grain size of cold-extruded gear steel after carburizing belongs to the field of metal material testing technology. The method mainly includes the following steps: taking samples from hot-rolled round steel and processing them into specimens of specified dimensions; normalizing the specimens; then performing spheroidizing annealing; cold-heading the spheroidized annealed specimens; then performing pseudo-carburizing treatment; finally, preparing the specimens into metallographic samples, etching them with picric acid aqueous solution, and observing the grain size under a metallographic microscope. This invention, through a coupled process of heat treatment and cold heading deformation, can effectively detect the austenite grain size of cold-extruded gear steel after carburizing, directly characterizing the material's resistance to grain coarsening during the carburizing process after cold extrusion.

The invention discloses application of a compound based on Schiff base as a fluorescent probe in detection of explosive picric acid. The structural formula of the compound containing the Schiff base structure is shown in the formula I. The specific structure is as follows: the probe has the characteristics of high selectivity, quick response and high sensitivity on picric acid. On the basis, the limitation of a single detection form is broken through, the sensor is developed into a dual-mode fluorescence sensor, and the sensor can stably exist in a system mixed with various different indicators; meanwhile, the dual-mode fluorescence sensor is flexibly combined with different material carriers such as PVA hydrogel, a PVDF film, a filter paper strip and the like, and the real-time, portable and intelligent field detection requirements can be met through'deep learning 'and small lightweight programs. In addition, the detection method is simple and convenient to operate and low in cost, and has the potential of large-scale popularization and application.

The present invention discloses a non-explosive picrate synthesis method, and relates to the technical field of chemical synthesis, the method selects picric acid, aromatic hydrocarbon, aromatic ether and the like as raw materials, and low alcohol or aromatic hydrocarbon is matched as a solvent. The synthesis method comprises an alcohol co-dissolution method, an azeotropic dehydration method and a mixed solvent method, and picrate is prepared through the operations of dissolution, mixing, cooling crystallization and the like. And reacting the product with raw materials, filtering, washing and drying to obtain the final product. According to the method, explosive dry picric acid is replaced by safe raw materials, so that the explosion risk is effectively reduced; reaction conditions are accurately controlled, and the product stability is improved; the reaction process is optimized, the reaction time is shortened, the synthesis efficiency is improved, the method is suitable for industrial large-scale production, and the prepared picrate has wide application prospects in the fields of fuel additives, medical intermediates and the like.

The application discloses a metallographic structure display corrosion agent suitable for Cu-containing martensite bearing steel and a display method, and the corrosion agent contains 3-5g of picric acid, 0.9-1.3g of hydrogen peroxide, 1.2-1.8g of hydrofluoric acid, 2.5-4g of nitric acid, 0.5-1g of fatty alcohol polyoxyethylene ether, 0.4-0.8g of fatty alcohol polyoxyethylene ether sodium sulfate and 0.3-0.5g of sodium dodecyl benzene sulfonate in 80-100g of water. According to the characteristics of the Cu-containing bearing steel, the corrosion agent formula is re-designed through experiments, the multi-acid is used in combination with multiple surfactants and oxidants, and the corrosion time can be controlled and the fine crystal phase structure morphology of the tempered martensite and the reversed austenite in the bearing steel can be obviously displayed.

The invention discloses a rapid cyanogenic glycoside detection kit and a detection method, and belongs to the technical field of agricultural product detection. The kit comprises an enzymolysis reaction reagent and a hydrocyanic acid detection reagent, the enzymatic hydrolysis reaction reagent is prepared from beta-glucosidase, 1-ethyl-3-methylimidazole diethyl phosphate salt and rhamnolipid, and the enzymatic hydrolysis reaction reagent is prepared from beta-glucosidase, 1-ethyl-3-methylimidazole diethyl phosphate salt and rhamnolipid; the hydrocyanic acid detection reagent comprises a picric acid test strip, tartaric acid and a saturated sodium carbonate solution. The detection method comprises the following steps: adding an enzymolysis reaction reagent into a sample to be detected, hydrolyzing cyanogenic glycoside into cyanide, and adding tartaric acid to convert into volatile hydrocyanic acid; a picric acid test strip wetted by a saturated sodium carbonate solution is used for adsorption, and hydrocyanic acid and sodium picrate on the test strip act to generate sodium isocyanurate; and observing the color change of the test strip for qualitative and / or quantitative detection. The detection kit provided by the invention is convenient and rapid, has a short detection period, and is convenient for timely detection in links of agricultural product production, processing, storage, sales and the like.

The invention provides a method for detecting a martensitic structure of a steel rail. According to the method, the polishing precision of the steel rail sample can be improved and the surface roughness can be reduced by combining electrolytic polishing comprising specific components and mechanical light polishing. Furthermore, according to the method, corrosion is carried out after mechanical polishing, the corrosive liquid comprising an alcohol and nitric acid mixed solution and a picric acid alcohol saturated solution is adopted, rapid display of martensite can be achieved, the overall method is simple in process and easy to operate, and the test efficiency is improved.

The invention relates to a dual-phase steel color metallographic coloring agent and a color metallographic display method thereof, belongs to the technical field of decoration agents for metal metallographic display, solves the technical problem that a conventional coloring agent contains picric acid, and adopts the technical scheme that the dual-phase steel color metallographic coloring agent is prepared from the following components in percentage by volume: 40-60% of a potassium metabisulfite solution with the concentration of 2-20%, 10-30% of a solvent and the balance of water. The volume sum of the potassium metabisulfite solution and the sodium metabisulfite solution is 100%, and mixing the potassium metabisulfite solution, the sodium metabisulfite solution and the potassium metabisulfite solution at room temperature. The method sequentially comprises the steps of sampling, coarse grinding, fine grinding, coarse polishing, fine polishing, coloring agent solution preparation, dyeing, microscopic structure observation and color image acquisition. The raw materials are convenient to store and low in price, and the dyeing process is simple and reliable; the coloring agent can replace a coloring agent containing picric acid, bainite and martensite structures can be clearly distinguished, and a guarantee is provided for recognition and quantitative detection of the microstructure of the steel grade.

The invention relates to the technical field of steel and iron material performance detection, in particular to a corrosive agent for displaying the original austenite grain boundary of 4Cr13 martensitic stainless steel, a preparation method of the corrosive agent and a corrosion method for displaying the original austenite grain boundary of the 4Cr13 martensitic stainless steel. The alcohol can dissolve more picric acid crystals, so that the concentration of picric acid in the corrosive is improved. The sulfuric acid solution has strong oxidizing property, can destroy a passive film (Cr2O3) on the surface of 4Cr13 steel, and enhances the infiltration capacity of picric acid to the grain boundary. The corrosion inhibitor enables the corrosive agent to uniformly cover the surface of a sample by reducing the surface tension of a solution, the corrosive agent is adsorbed on a matrix to inhibit corrosion after ionization, and the crystal boundary is promoted to permeate to the crystal boundary due to high free energy and weak adsorption, so that the crystal boundary is corroded preferentially.

The invention discloses an austenitic stainless steel welded joint metallographic corrosive agent and a corrosion method thereof, and belongs to the technical field of metal material detection. Dissolving picric acid in deionized water until the solution is saturated to obtain a saturated picric acid aqueous solution; dissolving ferric chloride and hydrochloric acid in a solvent to obtain a ferric chloride hydrochloric acid solution; and after the saturated picric acid aqueous solution and the ferric chloride hydrochloric acid solution are evenly mixed, a hand sanitizer containing a surfactant is added and evenly mixed, and the austenitic stainless steel welding metallographic corrosive agent is obtained. After the metallographic structure of the austenitic stainless steel welded joint is corroded, the metallographic structure is clear, dendrites and sizes of the austenitic stainless steel welded joint can be accurately distinguished, and then the metallographic structure, grain size and other data of the austenitic stainless steel welded joint can be accurately obtained, so that the welding process can be adjusted in time; the method is very important for improving the performance of the austenitic stainless steel welded joint.

The invention belongs to the technical field of martensitic stainless steel performance detection, and relates to a 4Cr13 stainless steel metallographic etchant and a corrosion method for displaying carbides, and the etchant is prepared from the following components: 10-15 mL of glacial acetic acid, 1-2 g of ammonium persulfate, 0.5-1 g of sodium molybdate, 70-80 mL of absolute ethyl alcohol and 10-15 mL of deionized water. Glacial acetic acid is organic weak acid, and compared with inorganic acid, glacial acetic acid is more environment-friendly and mild and can reduce grain boundary over-corrosion; ammonium persulfate is a mild oxidant, releases active oxygen in an acidic environment, selectively destroys a passive film, enhances grain boundary and phase boundary corrosion, and avoids use of strong acid or heavy metal. Molybdate ions in sodium molybdate are adsorbed on the surface of carbide to generate a MoO2 / MoO3 nano film, blue-black contrast is generated through light interference, the contrast of the carbide is remarkably improved, and toxic picric acid is replaced. Absolute ethyl alcohol is an environment-friendly organic solvent, so that the reaction rate is reduced, the uniformity is improved, and the method is environment-friendly.

The present invention relates to the technical field of tissue section staining, and in particular to a multicolor composite staining kit, a staining method, and applications thereof. The multicolor composite staining kit provided by the present invention not only achieves good staining effects and has a high degree of differentiation in staining different tissue structures, but also does not contain hazardous chemical components such as picric acid, ethanol, and ammonia, greatly reducing the associated risks and costs during production, storage, transportation, use, and disposal. In addition, the use of the kit of the present invention can effectively simplify the operating steps and reduce the difficulty of operation. While significantly improving the repeatability of the staining results, it is more environmentally and operator-friendly, has lower costs, and has good application prospects.

The application belongs to the technical field of fluorescent sensing detection, and particularly relates to a MOF-based composite material for multiple detection of Fe 3+ , MnO4 ‑ and picric acid and a preparation method thereof. The application prepares ZIF-8 by taking Zn(NO3)6H2O and 2-methyl imidazole as raw materials; and then the MOF-based composite material Flu@ZIF-8 is obtained by soaking in a Flu methanol solution. The application is the first multi-element fluorescent sensor based on the confinement effect of ZIF-8, and can realize efficient detection of Fe 3+ , MnO4 ‑ and PA synchronously, break through the limitation of traditional single target detection, effectively inhibit the ACQ effect of Flu, avoid solution pollution problems, and retain excellent optical properties. The material still maintains structural integrity and fluorescent response ability after multiple regeneration cycles, and reduces the cost of actual application.

The invention discloses a ferritic stainless steel metallographic corrosive as well as a preparation method and a corrosion method thereof, and belongs to the technical field of metal material detection. Dissolving picric acid in deionized water until the picric acid is saturated to obtain a saturated picric acid solution; uniformly mixing ferric chloride, hydrochloric acid and a solvent to obtain a ferric chloride hydrochloric acid solution; and uniformly mixing the saturated picric acid solution and the ferric chloride hydrochloric acid solution, adding the hand sanitizer containing the surfactant, and uniformly mixing to obtain the ferritic stainless steel metallographic corrosive. After the ferritic stainless steel is corroded, the metallographic structure of the ferritic stainless steel is clear, the dendritic crystal and the size of the ferritic stainless steel can be accurately distinguished, then the metallographic structure, the grain size and other data of the ferritic stainless steel can be accurately obtained, accordingly, the welding process can be adjusted in time, and the method is extremely important for improving the performance of the ferritic stainless steel.

The invention relates to a phase structure-based accurate analysis method for a rare earth phase in bottom slag of a zinc-aluminum-magnesium production line, which comprises the following steps of: sampling, roughly grinding, finely grinding, polishing and corroding, putting a polished sample into a corrosive agent for corroding for 1-2 seconds, then washing with alcohol, and blow-drying; then observing by a scanning electron microscope and determining components of phases by an energy disperse spectroscopy; a corrosive agent used for corrosion is prepared from an HF aqueous solution with the mass concentration of 0.01-0.05%, a nitric acid alcohol solution with the mass concentration of 0.1-0.5% and 1-3 ml of a picric acid aqueous solution saturated at room temperature. According to the method, the phase structure, morphology, size and distribution of the rare earth phase in the bottom slag can be displayed and observed simply and rapidly at low cost, components of the rare earth phase in the bottom slag and the atomic ratio of all elements can be accurately determined through the energy disperse spectroscopy, and the method has the advantages of being low in detection cost, rapid, simple and accurate.

Pyrotechnic mixture with potassium benzanate, said pyrotechnic mixture comprising a binary or ternary intermixture comprising at least two selected from potassium benzanate, copper picramate and potassium picrate.

The application relates to the field of picric acid detection, and discloses a rapid visual detection method based on a perylene imide derivative. Specifically, a method for detecting picric acid is disclosed, wherein a perylene imide derivative with a structure shown in formula (I) is used as a probe. The probe has good water solubility, and can realize high-sensitivity, specific and visual detection of picric acid. The detection method provided by the application has high detection efficiency and sensitivity.

The present application relates to the technical field of multifunctional light-emitting liquid crystal, and particularly relates to a pyrone multifunctional light-emitting liquid crystal compound, a preparation method and application thereof, and a structure of the compound is shown as formula (I), wherein n is 10, 12 or 14. The target product can be prepared by reacting 3,4,5-trialkoxybenzaldehyde and 2,6-dimethyl-gamma-pyrone in the presence of sodium tert-butoxide in anhydrous ethanol, and then purified by recrystallization. The method is suitable for industrial production, because raw materials are easy to obtain, reaction conditions are mild, and purification is simple. The pyrone light-emitting liquid crystal compound provided by the present application combines the excellent light-emitting performance of pyrone and the supramolecular self-assembly characteristics of liquid crystal, and can be applied to the fields of bistable light-emitting materials, ferroelectric materials, light-emitting organic gels and picric acid fluorescent probes, and shows a broad application prospect.

The invention provides a treatment method of wastewater containing nitric acid, sulfuric acid and nitrophenol energetic compounds, and belongs to the field of solvent treatment. The method comprises the following steps: adsorbing wastewater containing nitric acid, sulfuric acid and nitrophenol energetic compounds by using resin to obtain adsorbed resin and filtrate; the resin is a polymer microporous spherical compound obtained by suspension polymerization of styrene and divinylbenzene; eluting the adsorbed resin by using a solvent medium to obtain an eluent; and drying the eluent. The resin obtained by suspension polymerization of styrene and divinylbenzene is used for adsorbing energetic compounds such as 2-nitrophloroglucinol, 2, 4-dinitro phloroglucinol and trinitro phloroglucinol in the wastewater, so that the safety of the subsequent process of distilling and recovering nitric acid and sulfuric acid can be effectively ensured; nitrophenol compounds can be collected and utilized as reactants of the next process, concentrated nitric acid and concentrated sulfuric acid in waste liquid can be recycled and utilized, and environmental pressure is reduced.

This invention discloses a polysubstituted furanopyridine compound, its preparation method, and its application in pharmaceutical preparation. The compound is a triphenyl-substituted furanopyridine compound. This series of compounds possesses excellent fluorescence properties and can be used as novel fluorescent sensing materials for the efficient detection of aromatic explosives, especially exhibiting rapid response to picric acid and high sensitivity in test strip detection systems. Furthermore, this series of compounds also exhibits excellent antibacterial and bacteriostatic functions, demonstrating its potential application value in the biomedical field. This invention also provides a method for preparing the above-mentioned polysubstituted furanopyridine compound, using acetophenone compounds and polysubstituted furans as raw materials. This synthetic method has advantages such as simple operation, wide substrate applicability, high atom utilization, and excellent yield. This synthetic strategy overcomes the limitations of traditional methods, eliminating the need for expensive catalysts, and achieving a target product yield of up to 80%.

The invention discloses an etching solution for displaying an original austenite grain boundary of low-alloy martensite wear-resistant steel. The etching solution is prepared from six components including an H2O2 solution with the volume concentration of 30%, FeCl3. 6H2O, CuSO4. 5H2O, oxalic acid, lauryl sodium sulfate and water. The preparation method comprises the following steps: dissolving lauryl sodium sulfate in water at normal temperature, and then heating to boiling; and naturally cooling to normal temperature, adding FeCl3. 6H2O, CuSO4. 5H2O, oxalic acid and a H2O2 solution with the volume concentration of 30%, and uniformly stirring and dissolving, thereby obtaining the catalyst. The etching solution provided by the invention is suitable for clearly displaying original austenite grain boundaries of low-alloy martensite wear-resistant steel with multiple hardness levels such as NM400, NM450, NM500 and NM550, hazardous chemicals such as picric acid and aqua regia do not need to be used, the operation is simple, and the cost is low.