碳纤维杆--碳纤维的组成结构的介绍

         碳(tan)(tan)纤(xian)(xian)(xian)(xian)(xian)(xian)维(wei)(wei)是(shi)(shi)含(han)碳(tan)(tan)量高(gao)(gao)于(yu)90%的(de)(de)(de)(de)(de)无机高(gao)(gao)分子纤(xian)(xian)(xian)(xian)(xian)(xian)维(wei)(wei)。其中含(han)碳(tan)(tan)量高(gao)(gao)于(yu)99%的(de)(de)(de)(de)(de)称石(shi)(shi)(shi)墨纤(xian)(xian)(xian)(xian)(xian)(xian)维(wei)(wei)。碳(tan)(tan)纤(xian)(xian)(xian)(xian)(xian)(xian)维(wei)(wei)的(de)(de)(de)(de)(de)微(wei)观结构(gou)类似(si)人造石(shi)(shi)(shi)墨，是(shi)(shi)乱层(ceng)(ceng)石(shi)(shi)(shi)墨结构(gou)。[5]  碳(tan)(tan)纤(xian)(xian)(xian)(xian)(xian)(xian)维(wei)(wei)各层(ceng)(ceng)面(mian)(mian)间(jian)(jian)(jian)(jian)的(de)(de)(de)(de)(de)间(jian)(jian)(jian)(jian)距约(yue)为3.39到3.42A，各平(ping)行(xing)层(ceng)(ceng)面(mian)(mian)间(jian)(jian)(jian)(jian)的(de)(de)(de)(de)(de)各个(ge)碳(tan)(tan)原子，排列不如石(shi)(shi)(shi)墨那样规整，层(ceng)(ceng)与层(ceng)(ceng)之间(jian)(jian)(jian)(jian)借范德华(hua)力(li)连接(jie)在一起(qi)。[6]  通(tong)常(chang)也(ye)把碳(tan)(tan)纤(xian)(xian)(xian)(xian)(xian)(xian)维(wei)(wei)的(de)(de)(de)(de)(de)结构(gou)看成(cheng)(cheng)由(you)两维(wei)(wei)有(you)序的(de)(de)(de)(de)(de)结晶(jing)和(he)(he)孔(kong)(kong)(kong)(kong)(kong)洞组(zu)成(cheng)(cheng)，其中孔(kong)(kong)(kong)(kong)(kong)洞的(de)(de)(de)(de)(de)含(han)量、大(da)(da)小(xiao)和(he)(he)分布对(dui)碳(tan)(tan)纤(xian)(xian)(xian)(xian)(xian)(xian)维(wei)(wei)的(de)(de)(de)(de)(de)性(xing)(xing)能影(ying)(ying)响(xiang)(xiang)(xiang)较大(da)(da)。[7]  当(dang)孔(kong)(kong)(kong)(kong)(kong)隙(xi)(xi)(xi)(xi)(xi)率(lv)低(di)于(yu)某个(ge)临界值时(shi)，孔(kong)(kong)(kong)(kong)(kong)隙(xi)(xi)(xi)(xi)(xi)率(lv)对(dui)碳(tan)(tan)纤(xian)(xian)(xian)(xian)(xian)(xian)维(wei)(wei)复合(he)材(cai)(cai)料的(de)(de)(de)(de)(de)层(ceng)(ceng)间(jian)(jian)(jian)(jian)剪(jian)(jian)切强(qiang)(qiang)度(du)(du)、弯曲强(qiang)(qiang)度(du)(du)和(he)(he)拉伸强(qiang)(qiang)度(du)(du)无明显的(de)(de)(de)(de)(de)影(ying)(ying)响(xiang)(xiang)(xiang)。有(you)些研究(jiu)指出，引起(qi)材(cai)(cai)料力(li)学(xue)性(xing)(xing)能下(xia)降(jiang)的(de)(de)(de)(de)(de)临界孔(kong)(kong)(kong)(kong)(kong)隙(xi)(xi)(xi)(xi)(xi)率(lv)是(shi)(shi)1%-4%。孔(kong)(kong)(kong)(kong)(kong)隙(xi)(xi)(xi)(xi)(xi)体积(ji)(ji)含(han)量在0-4%范围内(nei)时(shi)，孔(kong)(kong)(kong)(kong)(kong)隙(xi)(xi)(xi)(xi)(xi)体积(ji)(ji)含(han)量每增加(jia)1%，层(ceng)(ceng)间(jian)(jian)(jian)(jian)剪(jian)(jian)切强(qiang)(qiang)度(du)(du)大(da)(da)约(yue)降(jiang)低(di)7%。通(tong)过对(dui)碳(tan)(tan)纤(xian)(xian)(xian)(xian)(xian)(xian)维(wei)(wei)环氧树脂(zhi)和(he)(he)碳(tan)(tan)纤(xian)(xian)(xian)(xian)(xian)(xian)维(wei)(wei)双马来亚胺树脂(zhi)层(ceng)(ceng)压板的(de)(de)(de)(de)(de)研究(jiu)看出，当(dang)孔(kong)(kong)(kong)(kong)(kong)隙(xi)(xi)(xi)(xi)(xi)率(lv)超过0.9%时(shi)，层(ceng)(ceng)间(jian)(jian)(jian)(jian)剪(jian)(jian)切强(qiang)(qiang)度(du)(du)开始下(xia)降(jiang)。由(you)试(shi)验得知(zhi)，孔(kong)(kong)(kong)(kong)(kong)隙(xi)(xi)(xi)(xi)(xi)主要分布在纤(xian)(xian)(xian)(xian)(xian)(xian)维(wei)(wei)束之间(jian)(jian)(jian)(jian)和(he)(he)层(ceng)(ceng)间(jian)(jian)(jian)(jian)界面(mian)(mian)处。并且孔(kong)(kong)(kong)(kong)(kong)隙(xi)(xi)(xi)(xi)(xi)含(han)量越(yue)高(gao)(gao)，孔(kong)(kong)(kong)(kong)(kong)隙(xi)(xi)(xi)(xi)(xi)的(de)(de)(de)(de)(de)尺寸越(yue)大(da)(da)，并显著降(jiang)低(di)了层(ceng)(ceng)合(he)板中层(ceng)(ceng)间(jian)(jian)(jian)(jian)界面(mian)(mian)的(de)(de)(de)(de)(de)面(mian)(mian)积(ji)(ji)。当(dang)材(cai)(cai)料受力(li)时(shi)，易沿层(ceng)(ceng)间(jian)(jian)(jian)(jian)破坏，这也(ye)是(shi)(shi)层(ceng)(ceng)间(jian)(jian)(jian)(jian)剪(jian)(jian)切强(qiang)(qiang)度(du)(du)对(dui)孔(kong)(kong)(kong)(kong)(kong)隙(xi)(xi)(xi)(xi)(xi)相(xiang)对(dui)敏感的(de)(de)(de)(de)(de)原因(yin)。另外孔(kong)(kong)(kong)(kong)(kong)隙(xi)(xi)(xi)(xi)(xi)处是(shi)(shi)应力(li)集中区(qu)，承载(zai)能力(li)弱，当(dang)受力(li)时(shi)，孔(kong)(kong)(kong)(kong)(kong)隙(xi)(xi)(xi)(xi)(xi)扩大(da)(da)形(xing)成(cheng)(cheng)长(zhang)裂(lie)纹(wen)，从而遭(zao)到破坏。即(ji)使两种具有(you)相(xiang)同孔(kong)(kong)(kong)(kong)(kong)隙(xi)(xi)(xi)(xi)(xi)率(lv)的(de)(de)(de)(de)(de)层(ceng)(ceng)压板（在同一养护周(zhou)期运用(yong)不同的(de)(de)(de)(de)(de)预浸方法和(he)(he)制造方式），它们也(ye)表现处完全不同的(de)(de)(de)(de)(de)力(li)学(xue)行(xing)为。力(li)学(xue)性(xing)(xing)能随孔(kong)(kong)(kong)(kong)(kong)隙(xi)(xi)(xi)(xi)(xi)率(lv)的(de)(de)(de)(de)(de)增加(jia)而下(xia)降(jiang)的(de)(de)(de)(de)(de)具体数值不同，表现为孔(kong)(kong)(kong)(kong)(kong)隙(xi)(xi)(xi)(xi)(xi)率(lv)对(dui)力(li)学(xue)性(xing)(xing)能的(de)(de)(de)(de)(de)影(ying)(ying)响(xiang)(xiang)(xiang)离散性(xing)(xing)大(da)(da)且重(zhong)复性(xing)(xing)差(cha)。由(you)于(yu)包含(han)大(da)(da)量可变因(yin)素，孔(kong)(kong)(kong)(kong)(kong)隙(xi)(xi)(xi)(xi)(xi)对(dui)复合(he)材(cai)(cai)料层(ceng)(ceng)压板力(li)学(xue)性(xing)(xing)能的(de)(de)(de)(de)(de)影(ying)(ying)响(xiang)(xiang)(xiang)是(shi)(shi)个(ge)很复杂的(de)(de)(de)(de)(de)问题。这些因(yin)素包含(han)：孔(kong)(kong)(kong)(kong)(kong)隙(xi)(xi)(xi)(xi)(xi)的(de)(de)(de)(de)(de)形(xing)状(zhuang)、尺寸、位置；纤(xian)(xian)(xian)(xian)(xian)(xian)维(wei)(wei)、基体和(he)(he)界面(mian)(mian)的(de)(de)(de)(de)(de)力(li)学(xue)性(xing)(xing)能；静(jing)态或者动态的(de)(de)(de)(de)(de)荷载(zai)。相(xiang)对(dui)于(yu)孔(kong)(kong)(kong)(kong)(kong)隙(xi)(xi)(xi)(xi)(xi)率(lv)和(he)(he)孔(kong)(kong)(kong)(kong)(kong)隙(xi)(xi)(xi)(xi)(xi)长(zhang)宽比，孔(kong)(kong)(kong)(kong)(kong)隙(xi)(xi)(xi)(xi)(xi)尺寸、分布对(dui)力(li)学(xue)性(xing)(xing)能的(de)(de)(de)(de)(de)影(ying)(ying)响(xiang)(xiang)(xiang)更大(da)(da)些。并发现大(da)(da)的(de)(de)(de)(de)(de)孔(kong)(kong)(kong)(kong)(kong)隙(xi)(xi)(xi)(xi)(xi)（面(mian)(mian)积(ji)(ji)>0.03mm2）对(dui)力(li)学(xue)性(xing)(xing)能有(you)不利影(ying)(ying)响(xiang)(xiang)(xiang)，这归因(yin)于(yu)孔(kong)(kong)(kong)(kong)(kong)隙(xi)(xi)(xi)(xi)(xi)对(dui)层(ceng)(ceng)间(jian)(jian)(jian)(jian)富胶(jiao)区(qu)的(de)(de)(de)(de)(de)裂(lie)纹(wen)扩展的(de)(de)(de)(de)(de)产(chan)生影(ying)(ying)响(xiang)(xiang)(xiang)。