Wollastonite is a calcium metasilicate mineral with a chemical formula of CaSiO 3 and a theoretical chemical composition of 48.3% CaO and 51.7% SiO 2 . Often white and grayish white, glass luster to pearl luster; density 2.78 ~ 2.9lg / cm 3 ; hardness 4.5 ~ 5.0; melting point 1544 ° C, soluble in acid, boiled with hydrochloric acid can produce flocculent silicon, small thermal expansion, low loss of ignition Good fluxing. It is widely used as a reinforcing filler for polymer matrix composites because of its non-toxicity, chemical resistance, thermal stability and dimensional stability, excellent mechanical and electrical properties, and reinforcing effects. However, the compatibility of the wollastonite powder with the polymer base is poor, so the direct dispersibility is not good. After the surface treatment, the compatibility with the polymer base can be improved, and the reinforcing effect is enhanced, so that the reinforcing effect is enhanced. The mechanical properties of the filled polymer-based composites are better [1, 2] . The United States was exploited in Willsboro, New York State, as early as 1933. The Chinese wollastonite mine was discovered in 1975. It was officially mined and tested in 1980. In 1981, the export gap was filled by the pear tree Dadingshan wollastonite. According to incomplete statistics, by the end of 2005, the annual output of wollastonite in China has reached 595,385 tons and the export volume is nearly 200,000 tons. It has become the world's first production of wollastonite and the export volume. One country [3] . I. Research status of surface modification of wollastonite The surface physical properties of wollastonite are purposely altered or given new functions depending on the needs of the application to meet the needs of modern new materials, processes and new technologies. The surface modification of wollastonite may use a coupling agent such as silane, aluminate or titanate , a surfactant such as stearic acid, a surfactant such as an unsaturated fatty acid, and an organic oligomer or two or more kinds of surfaces. The active agents are used in combination. There are four main methods for surface modification of wollastonite: mechanical chemical modification, coating method, coupling agent method and inorganic nano-coating modification method. Mechanochemical modification is the use of ultrafine pulverization and other strong mechanical effects to activate the surface of the powder purposefully, to some extent change the crystal structure, solubility properties (surface amorphization), chemical adsorption and reactivity of the particle surface. (increased surface active sites or reactive groups) and the like. Obviously, it is difficult to meet the requirements of the application field for the physical and chemical properties of the powder surface by simply modifying the surface by mechanical activation. However, mechanochemical action activates the surface of the powder and can increase the activity of the particles with other inorganic or organic substances. Free radicals or ions generated on the newly formed surface can initiate polymerization of styrene and olefins to form a polymer grafted filler. Therefore, if an appropriate amount of surface modifier is added at a certain stage or step in the pulverization process of the inorganic powder, the mechanical activation can promote the chemical adsorption or chemical reaction of the surface modifier molecule on the surface of the inorganic powder to achieve the pulverization. The purpose of modifying the surface of inorganic powder in the process [2] . Chibo et al [4] carried out surface modification of Hubei Daye wollastonite by mechanochemical adsorption method with good effect. The wollastonite ore is processed into 325 mesh powder, and stearic acid, WD-50 silane, KH-792 silane or the like is used as a modifier, and the wollastonite is surface-modified by a vibration mill. Grinding equipment such as vibrating mill can perform surface modification on the superfine pulverization of minerals, and strengthen the modification effect by using pulverizing mechanical chemistry. This method enables non-metallic minerals ultrafine grinding and surface modification techniques simultaneously to improve the efficiency of product processing. The principle of the process is: adding a certain amount of stearic acid (or WD50 silane, or KH-792 silane) to the wollastonite powder, mixing and pulverizing and activating by a supersonic jet mill. Wollastonite and stearic acid are in the supersonic airflow pulverizing chamber, which is affected by the high-pressure high-speed airflow generated by the nozzles from different directions. The wollastonite cracks along the weak cleavage bond, due to the breakage of the bond, the fresh surface An ionic bond or reactive site appears. Similarly, stearic acid is broken along the carboxyl group to form carboxylate ions and hydrogen ions. Since wollastonite and stearic acid are simultaneously placed in the pulverizing chamber of the jet mill, the fresh surface radicals generate mechanical chemical reaction or mechanical chemical adsorption with each other, and the ultrafine pulverization surface modification is completed at the same time. Li Zhen et al [5] used mechanical modification of wollastonite by jet mill and pre-evaluated the modification effect by IR analysis. The performance of wollastonite-filled polypropylene (PP) before and after modification was compared. . The results show that the modified wollastonite changes from hydrophilic oleophobic to oleophilic hydrophobic; when the stearic acid mass fraction is 1.5%, the tensile strength and impact strength of the modified wollastonite/PP composite are the most. it is good. Wu Weide et al [6] based on the mechanical properties of the wollastonite crystal structure, using mechanical mechanics principles, supersonic gas flow as mechanical force, superfine pulverization surface modification of wollastonite. The results of scanning electron microscopy and infrared absorption spectroscopy indicated that the surface of ultrafine wollastonite powder had fine stearic acid grafts, and the interfacial bonding strength of active wollastonite/rubber composites was significantly higher than that of unmodified wollastonite. / Rubber composite interface bond strength. Yang Chunrong et al [7] selected three kinds of wollastonite with different particle sizes, mixed with different proportions of stearic acid, and modified them by mechanical force chemical method respectively, and evaluated the activation rate by means of microscopy and infrared spectroscopy. The method was applied to verify and evaluate the modification effect of wollastonite. The results show that the mechanical chemical modification is effective, which not only achieves the purpose of chemical modification, but also protects the crystal structure of wollastonite. At the same time, it also superfine pulverizes wollastonite powder; experiments on activation rate show The amount of stearic acid 2% can make the best modification effect of wollastonite; the particle size analysis and activation rate of wollastonite powder before and after modification show that the particle size of wollastonite powder before modification is smaller, and the modified particle size The relative increase, the worse the modification effect, indicating that it is modified by mechanical force chemistry, and does not require the initial powder to have a high degree of fineness, thereby saving cost. Pigment coatings are a surface treatment technology that has emerged in recent years, including gas phase coatings, liquid phase coatings, and dry coatings. The liquid phase coating has the disadvantages of complicated process, large equipment investment and high energy consumption. The gas phase envelope and solid phase coating have the advantages of short process, simple operation, low equipment investment and low cost. However, the gas phase envelope has certain limitations on the choice of treatment agent. Studies have shown that [8] , the selection of suitable inorganic and organic surface treatment agents has a significant effect on improving the dispersibility and fluidity of wollastonite powder. The organic diethanolamine is a colorless oily liquid with a boiling point of 269.1 ° C, soluble in water and other organic solvents. To treat wollastonite powder, it is necessary to first bake the wollastonite powder in an oven to remove water and other adsorbates on the surface of the wollastonite powder. According to the surface adsorption theory, the NH group is more active than the OH group, the surface of the wollastonite powder easily adsorbs diethanolamine, and the wollastonite powder coated with diethanolamine has dispersibility and fluidity in the aqueous phase and the oil phase. There has been a noticeable improvement. This is because the wollastonite powder after the coating has a hydrophilic group and a lipophilic group. Inorganic anhydrous aluminum trichloride is a white crystal, which is strongly absorbed in the air and generates hydrogen chloride gas to form a white mist. The anhydrous aluminum trichloride is heated to 183 ° C sublimation, and is strongly hydrolyzed by water to form aluminum hydroxide and hydrochloric acid solution, and releases a large amount of heat. Using the characteristics of aluminum trichloride, the aluminum trichloride is sublimated into a combination of gas and water vapor to form aluminum hydroxide, which is adsorbed on the surface by wollastonite powder, and then calcined at a high temperature, and the aluminum hydroxide loses water at a high temperature of 800 ° C. , into aluminum oxide. The wollastonite powder after the coating is calcined at a high temperature to form aluminum oxide to be densely coated on the surface of the wollastonite powder. After the wollastonite powder is coated with the aluminum oxide, the dispersibility and fluidity are also improved, and the whiteness is also improved. The solid phase coating is prepared by mixing and grinding solid particles and solid particles to achieve modification. Its characteristics are flexible, easy to control, easy to operate, low energy consumption, and no environmental pollution. As long as the coating agent is selected properly, the improvement of the important indexes such as the color reduction rate and whiteness of the wollastonite powder is remarkable. The coupling agent (or chemical impregnation) method is a commonly used surface modification method with simple process and convenient operation [9] . For example, the surface modification of wollastonite by MMA: weigh a certain amount of wollastonite powder into a three-necked flask, add water and MMA in proportion, stir vigorously, slowly increase the temperature to 70-75 ° C, and add according to the monomer amount. 0.6% to 0.7% of a water-soluble initiator, which is filtered after a period of reaction. Dry in a 120 ° C oven to a constant mass and set aside. Studies have shown that the surface properties of the wollastonite particles coated with polymethyl methacrylate improve the mechanical properties of the matrix resin, especially the small particle size modified rigid wollastonite for performance improvement. Hu Yuchang used a silane solution to modify the surface of wollastonite. First, the wollastonite is ground to 2 to 3 mm, repeatedly washed with petroleum ether, dried, and then immersed in a silane solution having a pH of 3 to 5 for 3 to 5 hours, and dried at 150 to 180 °C. After treatment, the electrical and chemical properties of wollastonite have changed significantly. Zhou Xinmu et al [10] used four methods to modify wollastonite. Method A: grinding the modifier into a fine powder and uniformly mixing the wollastonite powder in a jet mill; Method B: forming the filler into a slurry, adding a modifier solution, and standing and separating after vigorous stirring Drying; Method C: directly heating the modifier into a liquid spray to the surface of the high temperature filler under strong stirring, and controlling the temperature to continue to vigorously stir for a certain time at 90-100 ° C; Method D: mixing the filler and the modifier, using The ball mill performs ball milling. The wollastonite powder was surface-modified with the same amount of modifier (1.5%) and the same modification method (method C) using sodium oleate, aluminum titanate and stearic acid as modifiers, respectively. The results show that the modification effect is better with aluminum titanate and stearic acid as modifiers. Method C is the most ideal. This method can be used in high speed kneading machine in industry, with large processing capacity and simple operation. 1.2%～1.5%, the whiteness of wollastonite after modification is still above 85%, the whiteness of wollastonite is not affected when the modifier dosage is below 2%; the modification effect is best when the stirring time is 15min . Yuan Shiping [11] used polyol fatty acid esters as additives to coat and modify wollastonite powder. The optimum conditions were as follows: the optimum amount of modifier was 0.7% of wollastonite powder; The coating temperature is 160±10°C; the coating time is preferably 10-15min; when the coating time is 10-15min, the rotor rotation speed is 2500r/min. Zhang Wenzhi et al [12] studied the DL-411-A type aluminate coupling agent modified wollastonite and its viscosity behavior in white oil dispersion medium. The results showed that: 0.2% aluminate coupling agent was used to change The viscosity of the wollastonite powder in the white oil is greatly reduced, the volume of sedimentation in the water is increased, and the oil absorption decreases with the increase of the amount of the coupling agent; while the filling amount of the system viscosity is increased, the modified wollastonite powder ratio is not changed. The wollastonite powder is 1 times higher; the water absorption decreases with the increase of the amount of the aluminate coupling agent, and the modification has no significant effect on the whiteness of the wollastonite powder in the temperature range of 85-93 °C. Kang Wen et al [13] using stearic acid as a modifier, the best conditions for the addition of stearic acid is 1.0% to 1.2%, and the modification temperature is 80-120 ° C when the stirring speed is 900r/min. Sex time is 20 to 30 minutes. The mechanism of wollastonite modification was discussed. Under certain temperature and time conditions, after strong mechanical force, stearic acid first dissociated to form carboxylate ion [R-COO]-, carboxylate ion and silicon The active sites on the surface of the limestone produce chemisorption and chemical bonding to modify the wollastonite surface. The process flow is: wollastonite powder → preheating drying → modification treatment → cooling → degranulation → active wollastonite powder. Ding Hao [14] in the wollastonite mixing wet ultrafine grinding, surface modification of wollastonite with stearylamine salt. The results showed that the dosage, slurry conditions and grinding conditions all affected the modification effect. When the amount of stearylamine salt was 1.0%-1.2%, the activation rate was over 90%, and the modification effect was the best; The pulp conditions have pH, temperature and concentration. With the increase of the pH value of the slurry, the modification effect of wollastonite is gradually enhanced. In the wide range of pH>5, the modification of wollastonite has a good effect; with the increase of pulp temperature, the modification effect It has been enhanced, and the activation rate is as high as 97.5% at 70 °C. The modification effect is best when the slurry concentration is 40%. The grinding conditions affecting the modification effect include modification time, stirring speed and medium to material ratio. As the stirring speed increases, the activation rate of the modified wollastonite increases gradually, but the amplitude is small. In the range of 800 ~ 1000r / min, the effect is better, the best modification time is 10min. The modification effect increases as the ratio of the media to material increases. Li Zhen et al [15] invented a method for modifying wollastonite, the steps of which are as follows: the wollastonite powder is stirred at a constant temperature of 60 ° C for 10 min; then the titanate coupling agent TC-114 and thinner The mixture of anhydrous xylene was stirred at room temperature for 15 minutes while being sprayed at 60 ° C, and then slowly cooled to room temperature to obtain a dry modified powder. The coupling agent is used in an amount of 0.5% to 3.0% of wollastonite, and the coupling agent is mixed with the diluent 1:1 to 5. The stirring speed was 500 r/min. This invention changes the surface properties of the wollastonite particles, making the original hydrophilic oleophobicity, hydrophobic and lipophilic, and easily bonded to the polymer. Shen Jian et al [16] coated wollastonite with polyethylene glycol. When the amount of polyethylene glycol was 4% of wollastonite, the notched impact strength and low temperature performance of filled PP were effectively improved. Inorganic nano-coating is a method that has emerged in recent years. When wollastonite is used as a filler in rubber or plastic, it is generally subjected to surface organic modification treatment to enhance its compatibility with the matrix. However, surface organic modification can not significantly improve the sharp edges and corners formed when the particles are pulverized, and the effect of flat cleavage on the properties of the composite. This is because the corners and cleavage planes of the wollastonite in the composite material become stress concentration points when forming an interface with the organic matter, which directly affects the filling performance. If a layer of nano-sized particles is coated on the surface of the rigid particles, the composite can retain the strength brought by the rigid particles and improve the bonding interface between the particles and the organic matter. Huang Jiamu et al [17] mixed water glass and wollastonite powder in a certain ratio to prepare a solution, and then heated the solution to a suitable temperature, adding an appropriate amount of hydrochloric acid and water glass to react, and the resulting nano-SiO 2 grains were coated. On the wollastonite, a nano-SiO 2 coated wollastonite inorganic composite powder is obtained. The single wollastonite powder and the nano-SiO 2 coated wollastonite powder after surface treatment with 1.5% aluminate coupling agent are respectively filled with PP resin at 15%, 20%, 25%, 30% (mass ratio). The results show that under the same filling amount, the nano-SiO 2 coated wollastonite powder contributes significantly better to the tensile properties of PP than the uncoated wollastonite powder, and the maximum added value can reach 18.8% (at 30 % fill amount). Under the premise of ensuring that the tensile strength of PP does not decrease much, the nano-SiO 2 coated wollastonite powder can obtain a larger filling amount than the single wollastonite powder, and thus the economic utilization value is higher; the single wollastonite powder is concentrated. The impact resistance of propylene is not significantly improved. Nano-SiO 2 and coated wollastonite powder fill PP, which greatly increases the impact resistance of PP. It is still higher than the impact strength of unfilled PP when the filling amount is 25%. . Zhao Yulong et al [18] prepared silica/wollastonite composite particles with wollastonite and water glass as the main raw materials. It is found that the surface of the composite particles is passivated, which improves the bonding interface with polypropylene (PP). The study on the mechanical properties of PP filled with composite particles shows that the composite particles significantly improve the yield strength and bending strength of the composite. The breaking strength did not improve significantly, but the impact properties decreased. Hao Zengheng et al [19] coated a layer of nano-calcium carbonate on the wollastonite surface and treated the composite particles with a titanate coupling agent. The experimental method is as follows: the coated composite particles are dried at 100-110 ° C for 2 h, and then pre-stirred for 5 min in a high-speed mixer, and then the metered titanate coupling agent is diluted with liquid paraffin by a volume ratio of l:1. Spray evenly onto the coated composite particles at an appropriate temperature and stir until the reaction is complete. The composite particles treated by this method filled the plastic products, and the results showed that the tensile strength, notched impact strength and bending strength of the plastic were significantly higher than those of the unmodified coated composite particles. Liu Guihua et al [20] prepared aluminum silicate/wollastonite composite powder by using aluminum sulfate and sodium silicate as coating modifiers and coating nano-sized aluminum silicate on the surface of wollastonite by chemical precipitation method. . The composite particles were characterized by SEM, BET specific surface area meter, particle size analyzer, whiteness meter, oil absorption and energy spectrum analysis. The preparation conditions, such as coating amount, reactant concentration, reaction time, temperature, The effect of feed rate, etc. on the performance of composite particles. The results show that the surface of the wollastonite is uniformly coated with a layer of nano-sized aluminum silicate, and the whiteness is improved by 2.0%. Second, the application of surface modified wollastonite Wollastonite for fillers is the most potential, highest value added, and fastest growing application area. In the rubber and plastics industry, it mainly uses the similar fiber-reinforced effect produced by the needle-like crystal of wollastonite to replace the more expensive glass fiber, carbon fiber and asbestos reinforcing materials, and wollastonite can also improve the product. The role of performance. The main functions of modified acicular wollastonite ultrafine powder applied to engineering plastics as fillers are: improving the mechanical properties and anti-aging properties of plastic products; improving the functional strength of plastic products, reinforcing and reinforcing; improving the size of products Stability; adjust the rheological properties of plastics; replace the more expensive glass fiber as a filler, which can partially replace the high-priced plastics, thus reducing the cost of the product. At present, wollastonite is mainly used for nylon 6, nylon 66, polytetrafluoroethylene, polypropylene (PP), polyethylene, polyester, polycarbonate, polystyrene and polyolefin masterbatch. However, most of them are used in nylon 6 and nylon 66 engineering plastics, and the filling amount can reach 40%. Wang Xueqin and Li Binyao [21] added 2000 mesh wollastonite to nylon 66 with 40% filling. After modification, the mechanical properties were measured, tensile strength was 96.8 MPa, bending strength was 174.6 MPa, and pure Compared with the system, the ratio was increased by 23.5% and 57.4%, respectively, and the appearance of the sample strip was smooth. It shows that high content of wollastonite is beneficial to improve the mechanical strength and surface gloss of nylon 66 system. In addition to nylon 66, wollastonite is incorporated into polytetrafluoroethylene, polypropylene, polyolefin, polycarbonate and other resins, and studies have shown that it can improve performance and reduce cost. Zhou Xinmu and others used aluminum-titanium coupling agent and stearic acid as modifiers to modify wollastonite and filled the modified wollastonite into engineering plastics to improve the mechanical and thermomechanical properties of the product. . Yu Langen, Liu Chuanbing et al [22] made the fibrous crystal form wollastonite of Zhejiang Changxing Wollastonite, made a superfine needle-like powder by special powder processing technology, and changed the surface of the powder with silane coupling agent. Sexual treatment, the product is applied to engineering plastics as a filler, which can completely replace the similar imported modified wollastonite powder. Its price is about 50% of the import, and it has strong market competitiveness and good development prospects. Nanjing Jinshan Automotive Engineering Plastics Co., Ltd. applied it to PP engineering plastics instead of glass fiber as reinforcing filler. The test results show that the flexural modulus and tensile strength of the modified acicular wollastonite ultrafine powder modified blending materials meet the requirements of glass fiber as reinforcing filler modified blending material, and the cost is lower than that of glass fiber. More than 30%. Wei Jianxin et al [23] analyzed the particle size, aspect ratio and SEM morphology of wollastonite samples processed by QS50, QS600 jet mill and JCF mechanical crushing equipment, which showed that shear and friction can be produced. The jet mill is a relatively ideal device that can superfinely crush wollastonite and ensure it has the best aspect ratio. Through the research on the surface chemical modification effect of ultrafine wollastonite powder, the optimum process conditions were determined: the modifier was stearic acid, the dosage was 2%; the modification time was 15-20 min; the modification temperature was 70 °C. The application of ultrafine modified wollastonite in rubber was discussed. The results showed that the mechanical properties of vulcanized film prepared by ultrafine modified wollastonite filled natural rubber were better, and the tensile strength was up to 21.93 MPa. Generally up to 19-20 MPa), the elongation can reach 642.0%, the hardness is 57 Shore, and the tensile strength and elongation are higher than that of the white carbon black filled vulcanized film. Ultrafine modified wollastonite is an excellent rubber reinforced and toughened filler material, which can replace expensive white carbon black in some fields and has a good development and application prospect. YNFWHl01 series active high aspect ratio acicular wollastonite (mineral fiber reinforced material) is a new product jointly developed by Yunnan Superfine Materials Co., Ltd. and National Engineering Research Center of Engineering Plastics. The product is made of high quality natural fibrous wollastonite ore. It is prepared from needle-shaped crystal protection technology and fiber surface coating technology. It has high aspect ratio and high activity. It has good compatibility with resin and its performance is different from traditional rigid particle filler (carbonic acid). calcium, talc powder) between the glass fiber reinforced material having properties of chopped glass fiber. The products have been widely used in Haier Kehua Company and Haier New Materials Co., Ltd., and have obvious enhancement effects in thermoplastics such as PP, PA66, PET and ABS. YNFWHl01 mineral fiber reinforced material is applied in PP. It can maintain the needle-like crystal form of active high aspect ratio wollastonite mineral fiber reinforced material during processing. The dosage can reach 50%, and each performance index can meet the technical index of products. It is required to have the performance advantages that traditional rigid particles are difficult to achieve. It can be used to produce high-filled PP, high-modulus PP and blended with glass fiber to enhance the demand of PP products in different industries. Blending with glass fiber can solve glass fiber. Orientation issues. The product has good compatibility with the resin, good fluidity in the extrusion granulation process, low wear on the equipment, excellent processing performance in the extrusion granulation and injection molding process, good surface smoothness of the product, and can effectively solve the glass Fiber exposed and other issues. Third, the conclusion The results of the use of many engineering plastics production enterprises show that the modified acicular wollastonite ultrafine powder is applied to engineering plastics with remarkable effects, and it is the application field with the highest added value of wollastonite products. More than 10 companies in Shanghai, Nanjing, Beijing, Suzhou, and Zhejiang Jiande have already used the product in batches. Undoubtedly, the application of modified acicular wollastonite ultrafine powder to engineering plastics will have a good market prospect. [references] [l] Editorial Committee of the Non-Metallic Mining Industry Manual. Non-metallic mineral industry manual (2) [M]. Beijing: Metallurgical Industry Press, 1992: 1108-1110. [2] Zheng Shuilin. Powder surface modification (Second Edition) [M]. Beijing: China Building Materials Industry Press, 2004: 29-116. [3] Zhang Mengxian. Current status and application of deep processing of wollastonite in China [J]. China Non-Metallic Mining Industry Guide, 2006, (Supplement): 94-96. [4] Chi Bo, Shen Shangyue, Li Zhen, et al. Experimental study on surface modification of wollastonite [J]. Rock and Mineral Testing, 2001, 20 (1): 57-58. [5] Li Zhen, et al. Study on the properties of mechanically chemically modified wollastonite/polypropylene [J]. Plastics Industry, 2003, 31 (9): 35-36. [6] Wu Weide, et al. Mechanism of mechanically chemically modified wollastonite [J]. Bulletin of Mineralogy, Geochemistry, 1999, 18(4): 274-275. [7] Yang Chunrong, Li Zhen, Peng Jirong. Mechanical and chemical modification of wollastonite and its effect analysis [J]. Non-metallic minerals, 2003, 26 (1): 22-23. [8] Chen Guobin. Study on coating modification of wollastonite powder [J]. Rare metals and hard alloys, 2002, 30(3): 26-28. [9] Wu Xueming, Wang Lan, Huang Jianzhong, et al. Study on wollastonite filled modified rigid polyvinyl chloride [J]. China Plastics, 2002, 16 (1): 28-32. [10] Zhou Xinmu, Zhao Guanghao, Li Baoyou, et al. Wollastonite powder modification and its application in building plastics [J]. New building materials, 2005, (12): 57-58. [11] Yuan Shiping, et al. Study on modification of wollastonite powder and its application in inner tube [J]. Rubber Industry, 1997, 44: 657-660. [12] Zhang Wenzhi, Zhang Wengong, Tang Yongyan, et al. Study on coupling activation modification of wollastonite powder [J]. Plastics, 2005, 34 (1): 69-72. [13] Kang Wen, Zhou Chunwei, Ge Jinlong. Wollastonite modification research [J]. Journal of East China Institute of Technology, 2006, 29(2): 146-149. [14] Ding Hao. Study on stearylamine modified wollastonite in ultrafine grinding by agitating and grinding method [J]. China Powder Technology, 2005, (11): 29-32. [15] Li Zhen, et al. A method for modifying wollastonite [P]. China Patent. 2, 2003-12-24. Enclosed Laser Marking Machine Enclosed Laser Marking Machine,Enclosed Fiber Laser,Enclosed Fiber Laser Marking Machine,Best Enclosed Fiber Laser Feiquan Laser Technology Wuxi Co., Ltd. , https://www.fq-lasers.com