含纳米CaCO_3的镁钙中间包涂料对锰钢中Mn、C和总氧含量的影响

为了研究含纳米Ca CO3的镁钙质中间包涂料在冶炼过程中对钢水中Mn、C和总氧含量的影响,按90%(w)电熔镁砂和10%(w)纳米Ca CO3并外加2%(w)的Si O2微粉制成镁钙中间包涂料,并浇注成坩埚试样,自然养护24 h后于200℃下烘烤24 h,然后将盛有锰钢的镁钙质坩埚放入感应炉中,抽真空后通入氩气并保持氩气流动,随后将炉温升至1 100℃保温50 min,再继续升温至1 600℃使钢样熔化,然后每隔一段时间对钢水取样,检测钢样的Mn、C和总氧含量,同时对试验后坩埚制样进行电镜和能谱分析。结果表明:在冶炼过程中,钢水中Mn、C含量降低,总氧含量增加,这与纳米Ca CO3分解产生的CO2与钢中Mn、C元素的反应有关。     

含铝粉的MgO-SiC材料对IF钢硅含量的影响

以电熔镁砂、碳化硅和铝粉为主要原料,采用热固性酚醛树脂为结合剂,以等静压(200 MPa)压制成坩埚,自然养生24 h后于230℃保温24 h热处理。随后在坩埚中加入5 kg的IF钢和120 g保护渣,然后放入感应炉中加热至1 600℃至钢水熔化,分别冶炼30 min、60 min、90 min、120 min和180 min后各取1份钢样,化验钢样中的硅含量,并对试验后试样与钢水的反应层进行XRD、SEM和EDAS分析。结果表明:耐火材料和钢液反应层中MgO-CaO-SiO2液相的形成有利于降低材料中SiC对钢水的增Si作用,而铝粉的加入会促进MgO-SiC材料中的SiC向钢中溶解。     

耐火材料对钢水杂质的影响

研究不同耐火材料在熔炼汽车用钢(IF)时对钢水中杂质的影响.研究含游离CaO耐火材料对全脱氧镇静钢(AR016)的净化作用.结果表明:用不同耐火材料熔炼时,钢水的杂质成分会发生变化.用镁碳耐火材料熔炼时,钢中C含量会明显增加.用镁铝耐火材料时,钢中Al含量会增加.用含游离CaO的镁钙耐火材料熔炼时,钢中杂质几乎不增加,而且对钢中某些元素,如:磷、硅、硫等还会有明显的降低,因此它是冶炼洁净钢用理想的耐火材料.     

镁质中间包涂料中六偏磷酸钠加入量对IF钢夹杂的影响

以电熔镁砂和六偏磷酸钠为原料,按六偏磷酸钠加入质量分数分别为1%、2%、3%、5%配制镁质中间包涂料,浇注成坩埚试样,加入IF钢样,在真空碳管炉中于1 600℃保温120 min进行熔炼试验。对试验后坩埚及IF钢样进行SEM和EDS分析,并检测试验后钢样中总氧含量及夹杂物元素的含量。结果表明:IF钢中O、C、P含量随着镁质中间包涂料中六偏磷酸钠加入量的增加而增多,而Mn、Si、Al、Ti则随着镁质中间包涂料中六偏磷酸钠加入量的增加变化不大。IF钢中的氧化物夹杂以P2O5和MnO为主。     

铸锭过程中氧化铝耐火材料的侵蚀

研究了合金钢对氧化铝耐火材料的侵蚀。以氧化铝坩埚作为研究对象,对其进行物理表征。将4种不同铸造温度和合金含量的钢在氩气条件下熔化,并测量接触角。然后,用X射线衍射、光学显微镜、扫描电子显微镜和能量散射X射线光谱测定法来分析铸锭对氧化铝耐火材料的侵蚀和腐蚀。结果表明其耐火性能不影响侵蚀和腐蚀,即钢水未发生渗透,但氧和脱氧钢合金的含量会影响基质的侵蚀。首先,锰与氧化铝反应,接着与硅反应形成锰铝硅酸盐。在最高铸造温度(1 580℃)下也会形成莫来石。钢-耐火材料界面上,铝取代硅酸盐,侵蚀增强。在莫来石形成区域,由于热膨胀不匹配,1.6587等级的17Cr Ni Mo76钢发生剥落。在粗粒级中只形成铬掺杂氧化铝。     

Al2O3-C耐火材料对超低碳钢的增碳作用

在空气中利用中频感应炉加热,研究了以Si为抗氧化剂的Al2O3-C耐火材料对超低碳钢的增碳作用.利用高频燃烧红外吸收法测定钢样中的碳含量,并对用后耐火材料进行了SEM和EDS分析.研究结果表明钢熔化后,炭的直接溶解机制造成钢水中碳含量迅速增加;随着保温时间的增加,"渗透-溶解"机制对钢水增碳占主导作用;同时,耐火材料与钢水接触部位生成反应脱炭层,反应脱炭层隔离了钢水与耐火材料的直接接触,进而减缓并停止耐火材料对钢水的增碳作用;空气中的氧通过渣向钢水中传递,氧和钢水中的碳发生反应对钢水产生脱炭作用,同时,碳氧平衡决定了在钢水的碳含量很低时,脱炭反应接近于平衡状态,钢水中的碳含量趋于平衡.     

钢包釉对钢中总氧含量及夹杂的影响研究

炼钢过程中出钢后钢渣附着在钢包工作衬壁上,形成钢包釉,对钢-耐火材料的反应产生重要影响,是钢中夹杂的主要来源之一,同时对钢中总氧含量也产生影响.本文通过设计不同钙硅比的钢包釉层,研究其对钢中总氧含量及夹杂物的影响.研究发现:铝镁质耐火材料与钢水直接接触时,耐火材料组分溶解进钢水中形成夹杂,增加了钢中的夹杂和总氧含量;耐火材料表面覆盖釉层时,耐火材料与钢水通过界面层间接反应,减少了钢中的夹杂和总氧含量.其中钙硅比高的界面层,钢中总氧含量低,夹杂的数量也少,但是夹杂的尺寸较大.     

含铝粉的MgO-SiC材料对钢水的增碳行为

分别以93%或96%的电熔镁砂(3~1mm,≤1mm,≤0.088mm)、4%的碳化硅粉(≤0.088mm)、3%或0的金属铝粉(≤0.088mm)为主要原料,配成含铝粉和不含铝粉的MgO-SiC试样,以热固性酚醛树脂为结合剂,在等静压压力机上以200MPa的压力压制成坩埚,自然养护24h后于230℃保温24h,然后在坩埚中加入5kg超低碳钢,并在钢样表面覆盖120g无碳保护渣,放入感应炉中加热至1600℃至钢水熔化,每隔30min取1份钢样,共取6份,化验钢样中的碳含量,并对试验后试样与钢水的反应层进行显微镜观察和EDAS分析。结果表明:SiC氧化形成的SiO2保护膜以及MgO-CaO-SiO2液相的形成,有利于降低SiC对钢水的增碳作用;金属铝粉的加入减少了SiC的氧化,并且可能对钢水产生脱氧作用,导致SiC向钢中增碳。     

镁质浇注料中纯铝酸钙水泥加入量对钢液总氧含量的影响

在实验室内研究了镁质浇注料中纯铝酸钙水泥加入量对钢液总氧含量的影响。结果表明 :当纯铝酸钙水泥加入量在 6 % (质量分数 ,下同 )以下时 ,随着纯铝酸钙水泥加入量的增加 ,钢样中的总氧含量随之增加 ;当纯铝酸钙水泥加入量超过6 %时 ,钢样中的总氧含量下降     

镁钙耐火材料对钢水的净化作用

研究了不同CaO含量的镁钙耐火材料与AR0 16钢水之间的作用。利用岩相、真空直读光谱分析仪、扫描电镜能谱等手段对镁钙耐火材料与钢水作用前后钢水和耐火材料的成分变化以及耐火材料的显微结构变化进行了研究。研究结果表明 :镁钙耐火材料在 16 0 0℃下与AR0 16钢发生作用后生成了新相 ;CaO含量大于 30 %的镁钙耐火材料与钢水作用 6 0min时脱S效果最佳 ;在本实验条件下 ,作用 30min可使钢中Al降到较低 ;增加镁钙耐火材料中的CaO含量可进一步降低钢中S和Al。     

Phospholipid content of foods

The content of total lipids and total and component phospholipids in ca. 140 foods was compiled in response to frequent requests for data by researchers in nutrition and medicine, and to fill the appar-ent need for a reliable up-to-date tabulation of recent data. Eggs, organ meats, lean meats, fish, shellfish, cereal grains and oilseeds are good sources of phospholipids, especially the choline phosphatides: phosphatidylcholine, sphingomyelin and lysophosphatidylcholine. Leafy vegetables, fruiting parts, roots and tubers are, with few ex-ceptions, relatively poor dietary sources of total lipids and phospho-lipids. Foods or tissues in which the phospholipids perform similar functions also have similar relative phospholipid distributions. The data were tabulated by food group in separate tables with appropri-ate discussion. The use of conversion factors for calculating the total and individual phospholipids, sources of error, and research needs are discussed.     

总溴含量的测定方法

研究了PTA行业中总溴含量的测定方法,通过Na_2S_2O_8-NaOH体系对样品进行消解后,用抗坏血酸还原高价态无机溴,而后通过电位滴定法滴定消解产物中的溴离子来测定样品中的总溴含量。通过一些标准样品的测试和某PTA生产厂家的残渣浆料的验证,均有很高的符合度,认为该方法可以用于PTA行业中的总溴含量测定。     

Relation between the petrographic content of mineral components in coal and its ash content

Empirical and analytical relations are established between the content of mineral inclusions Ml determined by petrographic analysis of the coal according to State Standard GOST 94.14–93 and the ash content A ^d of dry coal according to State Standard GOST 11022-95. In the empirical approach, statistical methods yield relations between Ml and A ^d in the form of regression equations for coals of a particular region and a system of beds with a complex set of minerals. In the more general analytical approach, Ml is divided into microcomponents (sulfides, carbonates, clay materials, quartz, etc.). Taking account of the densities of the components and their transformation on combustion, a quantitative relation between Ml and A ^d may be established for specific coals or their fractions in enrichment.     

Lipide content of rice bran

Summary The examination of rough rice of eight varieties grown in three locations each showed variations in milling yields and lipide contents of bran and of the true pericarp and bran fraction which are attributable to the influence of variety and environment of growth. The average values found on the moisture-free basis were 6.0% bran and 5.4% true pericarp and germ fraction for the rough rice and 19.5 and 21.8% lipides in the bran and the true pericarp and germ fraction, respectively. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

Aflatoxin content of peanut hulls

The degree of aflatoxin contamination in peanut hulls was determined by analyzing inoculated hand-shelled hulls and hulls from peanuts known to contain aflatoxin. Hulls adjusted to 20% moisture, inoculated withAspergillus flavus, and incubated 7 days at 25 C supported growth ofA. flavus but not aflatoxin production. Peanuts from 20 selected Segregation III (visibleA. flavus) lots contained 13–353 ppb of aflatoxin. The machine-shelled hulls from these lots were analyzed and 3 lots contained no detectable aflatoxin, 13 lots contained 4–88 ppb and 4 lots contained >116 ppb. Aflatoxin concentrations of 53–87 ppb were detected in hulls when peanuts containing relatively high levels of aflatoxin (up to 26.8 ppm in damaged kernels) were carefully machine-shelled. Hulls from the same samples obtained by hand-shelling contained no detectable aflatoxin. When machine-shelled hulls were screened through successively smaller screens, the aflatoxin concentration of the smallest fraction (<3.18 mm) was always highest and indicated that small peanut kernels and peanut parts in the hulls actually contained the aflatoxin. Separating hulls over a 4.76 mm round-hole screen appeared to provide a means of removal of most aflatoxin in peanut hulls. No aflatoxin was found in hulls from uncontaminated peanuts.