超硬材料工具纳米SiO2酚醛树脂结合剂的制备与性能研究

本文通过溶胶凝胶法制备了纳米SiO2／酚醛树脂，采用红外光谱、X-衍射和热分析对其结构进行了表征。研究表明随着SiO2含量的增加，纳米SiO2／酚醛树脂树脂的热稳定性不断提高，采用纳米SiO2／酚醛树脂制备的树脂磨具的拉伸强度和冲击强度都有所提高。含量10％的纳米SiO2／酚醛树脂的初始热分解温度比纯酚醛树脂提高59℃，由该树脂制备的树脂磨具的拉伸强度比纯酚醛树脂提高14．8％。     

Curing mechanism of alkaline phenolic resin with organic ester

To study the curing mechanism of alkaline phenolic resin with organic ester, three esters were chosen to react with three systems - alkaline phenolic resin, potassium hydroxide aqueous solution containing phenol, and potassium hydroxide aqueous solution. The variations of pH, heat release and gel pH during the reactions were monitored and measured. Infrared spectroscopy （IR） and thermal gravity analysis （TG） techniques were used to characterize the curing reaction. It was found that organic ester is only partial y hydrolyzed and resin can be cured through organic ester hydrolysis process as wel as the reaction with redundant organic ester. The sequential curing mechanism of alkaline phenolic resin cured by organic ester was identified as fol ows： a portion of organic ester is firstly hydrolyzed owing to the effect of the strong alkaline; the gel is then formed after the pH decreases to about 10.8-10.88, meanwhile, the redundant organic ester （i.e. non-hydrolysis ester） starts the curing reaction with the resin. It has also been found that the curing rate depends on the hydrolysis velocity of organic ester. The faster the hydrolysis speed of the ester, the faster the curing rate of the resin.     

Application conditions for ester cured alkaline phenolic resin sand

Five organic esters with different curing speeds: propylene carbonate(i.e. high-speed ester A); 1, 4-butyrolactone; glycerol triacetate(i.e. medium-speed ester B); glycerol diacetate; dibasic ester(DBE)(i.e. lowspeed ester C), were chosen to react with alkaline phenolic resin to analyze the application conditions of ester cured alkaline phenolic resin. The relationships between the curing performances of the resin(including pH value, gel pH value, gel time of resin solution, heat release rate of the curing reaction and tensile strength of the resin sand) and the amount of added organic ester and curing temperature were investigated. The results indicated the following:(1) The optimal added amount of organic ester should be 25 wt.%-30 wt.% of alkaline phenolic resin and it must be above 20 wt.%-50 wt.% of the organic ester hydrolysis amount.(2) High-speed ester A(propylene carbonate) has a higher curing speed than 1, 4-butyrolactone, and they were both used as high-speed esters. Glycerol diacetate is not a high-speed ester in alkaline phenolic resin although it was used as a high-speed ester in ester cured sodium silicate sand; glycerol diacetate and glycerol triacetate can be used as medium-speed esters in alkaline phenolic resin.(3) High-speed ester A, medium-speed ester B(glycerol triacetate) and low-speed ester C(dibasic ester, i.e., DBE) should be used below 15 °C, 35 °C and 50 °C, respectively. High-speed ester A or lowspeed ester C should not be used alone but mixed with medium-speed ester B to improve the strength of the resin sand.(4) There should be a suitable solid content(generally 45 wt.%-65 wt.% of resin), alkali content(generally 10 wt.%-15 wt.% of resin) and viscosity of alkaline phenolic resin(generally 50-300 mPa·s) in the preparation of alkaline phenolic resin. Finally, the technique conditions of alkaline phenolic resin preparation and the application principles of organic ester were discussed.     

酚醛树脂改性及在超硬磨具中的应用研究现状

从有机物改性酚醛树脂、无机物改性酚醛树脂和纳米材料改性酚醛树脂三方面综述了酚醛树脂改性的研究现状,阐述了改性酚醛树脂在超硬树脂磨具中的应用,指出了酚醛树脂在超硬磨具应用中存在的问题并提出了解决思路。     

改性酚醛树脂金刚石砂轮磨削性能的研究

本文通过对比磨削试验,研究了普通酚醛树脂和两种改性酚醛树脂制作的金刚石砂轮的磨削性能.试验结果表明,通过改性提高树脂的力学性能可以增强结合剂对磨料的把持力,从而提高砂轮的磨削比;通过改性提高树脂的耐热性,防止磨削区域过热引起的树脂降解,从而保证了结合剂对磨料的把持力不降低,对砂轮的磨削比提高效果更为显著.同时通过对树脂...     

紫外光固化酚醛树脂的制备及在涂附磨具中的应用

本文通过丙稀酸与环氧酚醛树脂开环反应,制备出能紫外光固化的酚醛树脂结合剂,研究了制备该树脂的合适工艺条件为:催化剂N,N-二甲基苯胺的用量为体系总质量的1%,反应温度为80±5℃,反应时间为5~7h;用这种可紫外光固化的酚醛树脂制作的涂附磨具试样,不仅固化速度快,仅需4~5m in即可固化完全,而且磨削比是常规热固化试样的3倍多,使用性能大大提高。     

聚酰亚胺树脂和酚醛树脂在干湿条件下的磨削试验

本文研究了聚酰亚胺树脂和酚醛树脂作为砂轮结合剂的耐磨情况,通过力学性能测试、综合热分析和磨削实验对树脂进行性能表征。研究结果表明:(1)两种树脂的抗拉强度、抗折强度和冲击强度相差不大,但酚醛树脂的洛氏硬度偏低;(2)聚酰亚胺的耐高温性优良,最高分解温度达到623℃;(3)用聚酰亚胺作为结合剂制得的砂轮无论在干磨或者湿磨条件下都比酚醛树脂具有更优良的耐磨性,干磨时更明显。     

Study on direct-chain diacid modified phenolic resin for Al-alloy casting

1. Introduction The data shows that the oil consumption of a car is decreased by 6 %~8 % when its weight is reduced by 10%. So it is very clear that the cars' producers tend to reduce the weight of a car. Now the output of domestic cars is 20 million annually, the weight of light alloy casting per car is approximately 60 kg, while it has exceeded 100 kg in the developed countries. The total output of casting in China reaches 16.2 million tons, which is the largest in the world, being 1.3 time…     

超硬磨具用耐高温酚醛树脂结合剂的合成与表征

采用硼酸和N-(4-羟基苯基)马来酰亚胺(N-HPM)联合改性酚醛树脂(PF),制得具有良好耐热性和机械性能的PF。热分析实验结果表明:改性PF的耐热性能明显优于纯PF,改性PF失重10%的温度为490℃,比纯PF提高了130℃。实验结果表明:改性PF制得磨具样条的抗折和抗冲击强度比纯PF制得的样条均提高40%以上。     

粉末丁腈橡胶增韧改性酚醛树脂结合剂的研究

通过粉末丁腈橡胶与酚醛树脂密炼共混改性,研究了粉末丁腈橡胶占酚醛树脂10%、15%、20%、25%时磨具的力学性能和结构,并对比了密炼共混改性酚醛树脂、纯酚醛树脂和干粉共混改性酚醛树脂的差异.研究发现,丁腈橡胶与酚醛树脂在密炼共混改性后的相容性大大提高,组织均匀程度也大大提高;磨具的抗折强度、冲击韧性随着丁腈橡胶的加入...     

酚醛树脂用量对木陶瓷性能的影响

砂光木粉浸渍酚醛树脂经干燥、热压后在真空条件下烧结处理后制得了碳/碳复合材料(木陶瓷)。分析了酚醛树脂用量对木陶瓷尺寸收缩率、碳得率、力学性能、耐磨性的影响,并利用全自动元素分析仪检测了酚醛树脂用量对木陶瓷元素组成的影响,利用扫描电子显微镜(SEM)和X射线衍射(XRD)分析了酚醛树脂用量对木陶瓷微观形貌和结构的影响。结果表明,随着酚醛树脂用量的增加,木陶瓷的碳得率增大,尺寸收缩呈下降趋势,力学性能增强,耐磨性明显提高,木陶瓷中C、H含量降低,O、N的总含量升高;SEM观察结果说明,随着酚醛树脂用量的增加,木陶瓷内酚醛树脂碳化形成的玻璃碳更加明显,但对XRD谱图没有明显影响。当木粉与酚醛树脂的质量比为40∶60时,木陶瓷的结构与性能最稳定,并具有较好的力学性能和耐磨性。     

Study on preparation of fast curing novolaks for the shell process

1 .Introduction The shell process is unique in its ability to make excellentreproducible castings with better surface finish anddimensional tolerances than parts made by other sandcasting processes; also, the shell process is easier tooperate than other processes     

Influence of microwave irradiation on the preparation of novolacs for the shell process

1. IntroductionThe shell process is unique in its ability to makeexcellent reproducible castings with better surface finishand dimensional accuracy than castings made of othersand processes. It is also simpler to operate than many ofother casting processes [1-3]. Therefore, it has been widelyused in the foundry industry and presents a promisingfuture. In recent years the application of shell process inChina has been greatly increased and novolacs consumedin this process are up to tens of thou…     

油箱壳体冲压工艺与模具设计

针对油箱上下壳体的形状结构特点和生产要求,分析了油箱上下壳体的冲压成形工艺,制定了适合该油箱壳体生产要求的冲压工艺方案,介绍了油箱上下壳体冲压过程所使用的3副组合冲模的结构设计和工作过程。经生产验证:该油箱壳体采用的冲压工艺方案是有效而可靠的,对类似产品的生产具有一定的参考作用。     

高性能覆膜砂用酚醛树脂的制作工艺研究

介绍了一种高性能覆膜砂用酚醛树脂的制作工艺。从酚醛树脂的合成工艺入手，获得高强度的树脂基体．然后通过加入适当添加剂对树脂进行改性，最终获得了高性能的酚醛树脂。结果表明：采用适当的催化剂，调整树脂的反应温度，改变原料加入批次，加入改性剂，以及使用一种低分子物作为合成添加剂等多种工艺措施，可得到高强度、低游离酚、收率高的酚醛树脂。     

Improving the shear strength by silane treatments of aluminum for direct joining of phenolic resin

Phenolic resin was directly joined to aluminum using three different silane coupling agents, AEAPS (N-(β-aminoethyl)-γ-aminopropyl trimethoxy silane), McPS (γ-mercaptopropyl trimethoxy silane), and GPS (γ-glycidoxypropyl trimethoxy silane). The impacts of surface treatment conditions on the joint strength and interfacial properties were investigated. The joint strength was raised about 1.6–2.6 times that of the untreated aluminum when joined to phenolic resin. The chemical bonds were formed by the phenolic resin and the amino groups in AEAPS, while entanglement between the phenolic resin and the methylene groups in McPS was obtained. The results of cyclic thermal loading indicated that the interfaces were deteriorated and joint strength was decreased using GPS as the silane coupling agent when the number of cycles was increased. The interface was enhanced and the shear strength of joints was not decreased using AEAPS as the silane coupling agent.     

铜合金外壳弯曲工艺与模具设计

分析了一种铜合金外壳的弯曲工艺,计算了弯曲件的展开长度、落料力、冲孔力及弯曲力,阐述了影响弯曲件的回弹因素及凸凹模之间的间隙取值方法,介绍了壳体弯曲模具的结构设计,利用该模具生产的外壳完全符合技术条件的要求.     

铝合金壳盖压铸工艺优化研究

通过对铝合金壳盖压铸件进行实体造型,采用铸造数值模拟软件Z-Cast对铝合金壳盖压铸过程的压力场、速度场和温度场进行数值模拟,根据模拟结果分析浇注系统和溢流槽尺寸的合理性,重新设计、优化浇注系统的形状和布置位置,得到合理的压铸方案。对于铝合金压铸件结构和压铸工艺设计有着重要的指导意义。     

Bending strength and fracture surface topography of natural fiber-reinforced shell for investment casting process

In order to improve the properties of silica sol shell for investment casting process, various contents of cattail fibers were added into the slurry to prepare a fiber-reinforced shell in the present study. The bending strength of fiber-reinforced shell was investigated and the fracture surfaces of shell specimens were observed using SEM. It is found that the bending strength increases with the increase of fiber content, and the bending strength of a green shell with 1.0 wt.% fiber addition increases by 44% compared to the fiber-free shell. The failure of specimens of the fiber-reinforced green shell results from fiber rupture and debonding between the interface of fibers and adhesive under the bending load. The micro-crack propagation in the matrix is inhibited by the micro-holes for ablation of f ibers in specimens of the f iber-reinforced shell during the stage of being fired. As a result, the bending strength of specimens of the fired shell had no significant drop. Particularly, the bending strength of specimens of the fired shell reinforced with 0.6wt.% fiber reached the maximum value of 4.6 MPa.     

Preparation of carbon brushes with thermosetting resin binder

Carbon brushes with a resin binder were prepared according to an industrial process and the effects of the molding pressure, grains size and cure temperature on the properties of brush samples were discussed. The results show that the bulk density, bending strength and Rockwell hardness increase, while resistivity decreases with increasing molding pressure. Cure temperature has much more influence on the properties of brushes than molding pressure and grains size. Isothermal differential scanning calorimetry（DSC） was used to estimate the degree of cure of resin binder and a novel method of using the true density to measure the degree of cure of resin binder was presented and discussed briefly. Based on optimal process parameters carbon brushes were manufactured, durability tests for brushes were carried out on an alternate current motor and scanning electron microscope（SEM） was adopted to observe the morphology of worn surface of brushes. The results show that a luster oxide film can be formed on the surface of brushes and their service life reaches 380 h.