氧化对Al2O3—TiB2陶瓷刀具材料磨损特性的影响

研究了Ａｌ２Ｏ３－ＴｉＢ２陶瓷刀具材料的高温氧化特性以及氧化对刀具耐磨性能的影响。结果表明，随ＴｉＢ２含量的增加，Ａｌ２Ｏ３－ＴｉＢ２的氧化活化能降低，抗化能力下降。Ａｌ２Ｏ３－ＴｉＢ２刀具材料在加工淬火钢时，因切削高温的氧化作用在刀具表面生成的ＴｉＯ２既可将轻刀具的粘结磨损，又能起到固体润滑剂的作用，从而降低摩擦系数，因而提高刀具的耐磨性能。     

氧化对Al_2O_3－TiB_2陶瓷刀具材料磨损特性的影响

研究了Ａｌ_２Ｏ_３－ＴｉＢ_２陶瓷刀具材料的高温氧化特性以及氧化对刀具耐磨性能的影响。结果表明：随ＴｉＢ_２含量的增加，Ａｌ_２Ｏ_３－ＴｉＢ_２的氧化活化能降低，抗氧化能力下降．Ａｌ_２Ｏ_３－ＴｉＢ_２刀具材料在加工淬火钢时，因切削高温的氧化作用在刀具表面生成的ＴｉＯ_２既可减轻刀具的粘结磨损，又能起到固体润滑剂的作用，从而降低摩擦系数，因而提高刀具的耐磨性能。当切削速度大于１５０ｍ／ｍｉｎ时，随ＴｉＢ_２含量的增加，刀具抗磨损能力显著提高。     

TiB2的含量对Al2O3／TiG2陶瓷材料的高温氧化行为的影响

研究了不同ＴｉＢ２含量的Ａｌ２Ｏ３／ＴｉＯ２陶瓷材料的高温氧化行为。用ＸＲＤ和ＳＥＭ分析了材料氧化后的相组成及显微结构。探讨了该材料的氧化机理和氧化膜的破坏方式。结果表明：不同ＴｉＢ２含量的Ａｌ２Ｏ３／ＴｉＢ２陶瓷材料在１４００℃空气中氧化３０ｈ的氧化增重符合抛物线规律；随ＴｉＢ２含量的增加，材料的氧活化能降低，氧化后的强度损失率增大。     

TiB_2的含量对Al_2O_3／TiB_2陶瓷材料的高温氧化行为的影响

研究了不同ＴｉＢ２含量的Ａｌ_２Ｏ_３／ＴｉＢ_２陶瓷材料的高温氧化行为。用ＸＲＤ和ＳＥＭ分析了材料氧化后的相组成及显微结构。探讨了该材料的氧化机理和氧化膜的破坏方式。结果表明：不同ＴｉＢ２含量的Ａｌ２Ｏ３／ＴｉＢ２陶瓷材料在１４００℃空气中氧化３０ｈ的氧化增重符合抛物线规律；随ＴｉＢ２含量的增加，材料的氧化活化能降低，氧化后的强度损失率增大。     

SiC晶须对Al2O3／TiB2／SiCw陶瓷刀具材料高温断裂韧性的影响

研究了不同ＳｉＣ晶须含量的Ａｌ２Ｏ３／ＴｉＢ２／ＳｉＣｗ陶瓷刀具材料的断裂韧性随温度的变化规律。结果表明：Ａｌ２Ｏ３／ＴｉＢ２／ＳｉＣＷ陶瓷材料的Ｋ１Ｃ在１０００℃内随温度的升高而增大；晶须含量越大，通过计算分析表明，随温度的升高粘裂时拔出的晶须大大增多，当晶须体积含量（下同）为２０％时，Ａｌ２Ｏ３／ＴｉＢ２／ＳｉＣｗ陶瓷在室温时只有长径比小于２．８７的晶须在断裂时才有可能产生拔出，而在９００℃时     

C－B_4C－SiC复合材料抗氧化性能的研究

对碳／陶瓷复合材料（Ｃ－Ｂ＿４Ｃ－ＳｉＣ）的抗氧化性能进行了研究，结果表明：Ｃ－Ｂ＿４Ｃ－ＳｉＣ复合材料抗氧化性能比碳素材料大大提高，而且烧结助剂对Ｃ－Ｂ＿４Ｃ－ＳｉＣ复合材料的抗氧化性能影响很大。在复合材料中分别加入了Ａｌ，Ａｌ＿２Ｏ＿３，Ｎｉ，Ｔｉ，ＴｉＣ，Ｓｉ等不同烧结助剂，发现添加Ｎｉ的材料抗氧化性能最佳，经１０００℃氧化１５ｈ后，氧化度小于０．５％；加入Ｔｉ，Ｓｉ和ＴｉＣ的次之，不加烧结助剂的又次之，加入Ａｌ和Ａｌ＿２Ｏ＿３的最差。     

导电Al2O3基陶瓷刀具材料的超声—放电复合加工技术研究

采用超声－放电复合加工技术对Ａｌ２Ｏ３／（Ｗ，Ｔｉ）Ｃ，Ａｌ２Ｏ３／ＴｉＢ２，Ａｌ２Ｏ３／ＴｉＢ２／ＳｉＣｗ三种Ａｌ２Ｏ３基陶瓷刀具材料表面定位方孔进行加工，研究了共加工机理和加工参数对不同陶瓷材料加工效率，加工表面粗糙度的影响，由于该复合加工技术有产地结合了超扬波加工和放电加工的特点，因而能高效，高质量地加工陶瓷材料。试验结果表明，在同样的加工条件下，材料去除率的大小顺序为Ａｌ２Ｏ３／（Ｗ，Ｔｉ     

C—B4C—SiC复合材料抗氧化性能的研究

对碳／陶瓷复合材料（Ｃ－Ｂ４Ｃ－ＳｉＣ）的抗氧化性能进行了研究。结果表明：Ｃ－Ｂ４Ｃ－ＳｉＣ复合材料抗氧化性能比碳素材料大大提高，而且烧结助剂对Ｃ－Ｂ４ＣＳｉＣ复合材料的抗氧化性能影响很大。在复合材料中分别加入了Ａｌ，Ａｌ２Ｏ３，Ｎｉ，Ｔｉ，ＴｉＣ，Ｓｉ等不同烧结助剂，发现添加Ｎｉ的材料抗氧化性能最佳，经１０００℃氧化１５ｈ后，氧化度小于０．５％；加入Ｔｉ，Ｓｉ和ＴｉＣ的次之，不加烧结助剂的又次之     

反应合成AlN／TiB2复相陶瓷及残余应力分析

采用ＸＲＤ法研究了ＴｉＨ２，Ａｌ及ＢＮ反应过程中物相的生成机理，发现在不同温度下存在ＴｉＡｌ３，ＴｉＮ，－α－Ａｌ２Ｏ１等过渡相，但最终只有ＡｌＮ和ＴｉＢ２两相存在，并结合热力学分析，认为合成ＡｌＮ／ＴｉＢ２的反应温度应在１７００℃以上。通过反应热压法制备出了ＡｌＮ／ＴｉＢ２复相陶瓷，材料的三点弯曲强度为５３９ＭＰ，ＫＩＣ为５．０５ＭＰａ．ｍ＾１／２。     

激光熔覆Al2O3+TiO2复合陶瓷涂层的微观结构

研究了４５＃钢表面Ａｌ２Ｏ３＋ＴｉＯ２复合陶瓷激光熔覆层的微观组织和相结构、Ａｌ２Ｏ３＋ＴｉＯ２复合陶瓷激光熔覆涂层由α－Ａｌ２Ｏ３,ＴｉＯ２,γ－ＴｉＯ２,γ－Ａｌ２Ｏ３及Ａｌ２ＴｉＯ５相组成,消除了等离子喷涂层的层状组织特征,形成了大致方向的柱状晶,晶内为溶入了Ｔｉ及少量底层元素的α－Ａｌ２Ｏ３;晶界为由ＴｉＯ２和Ａｌ２Ｏ３形成的Ａｌ２ＴｉＯ５相,溶有少量的Ｃｒ,Ｆｅ,Ｙ取代了Ａｌ２ＴｉＯ５     

Self-lubricating behaviors of Al2O3/TiB2 ceramic tools in dry high-speed machining of hardened steel

In this paper, Al₂O₃/TiB₂ ceramic cutting tools with different TiB₂ content were produced by hot pressing. The fundamental properties of these ceramic cutting tools were examined. Dry high-speed machining tests were carried out on hardened steel. The tool wear, the cutting temperature, the cutting forces, and the friction coefficient between the tool and the chip were measured. It was shown that both the wear rates and the friction coefficient at the tool–chip interface of Al₂O₃/TiB₂ ceramic cutting tools in dry high-speed machining of hardened steel were reduced compared with that of in low-speed machining. The mechanisms responsible were determined to be the formation of a self-lubricating oxide film on the tool–chip interface owing to the tribological–chemical reaction by the elevated cutting temperature. The composition of the self-lubricating film was found to be the oxidation product of TiB₂ grains, which serves as lubricating additive on the wear track of the tool rake face. The appearance of this self-lubricating oxide film contributed to the improvement in wear resistance and the decrease of the friction coefficient. This action was even more effective with higher TiB₂ content. Cutting speed was found to have a profound effect on the self-lubricating behavior. In dry low-speed machining of hardened steel, the Al₂O₃/TiB₂ tools showed mainly adhesive and abrasive wear. While in dry high-speed machining, oxidation wear of the ceramic tools was the dominant mechanism due to the very high cutting temperature. No oxide film was formed on the tool–chip interface while machining in nitrogen atmosphere, and the tool wear resistance was correspondingly decreased.     

Influence of annealing temperature on microstructure evolution of TiAlSiN coating and its tribological behavior against Ti6Al4V alloys

TiAlSiN multicomponent coating, owing to its high hardness and excellent high temperature resistance, was widely used in the cutting field of difficult-to-cut materials such as titanium alloys. For machining titanium alloys, high temperature is easy to gather on the tool chips and deteriorate the cutting tools. Moreover, high temperature will also promote the microstructure evolution and make the wear mechanism more complex. In this paper, TiAlSiN coatings were deposited on cemented carbides and annealed at 400 °C, 600 °C and 800 °C respectively for 60 min in air, followed by reciprocating friction tests against Ti6Al4V counterparts. AFM, SEM, EDS and XPS were applied to investigate the microstructure evolution and tribological behavior of TiAlSiN coating after high temperature annealing. The results demonstrated that the oxidation resistance of TiN phase in TiAlSiN coating was worse than Si₃N₄ and AlN phases. These nitrides can be oxidized to TiO₂, SiO_x and AlO_x under 600 °C, and the depth of oxide layer was increased with the rising annealing temperature, resulting in the coarsened microstructure. The wear mechanisms of as-deposited TiAlSiN coating were oxidation wear and adhesion wear. With the rising annealing temperature, abrasive wear was gradually enhanced. For the TiAlSiN coating annealed at 800 °C, abrasive wear became the dominant wear mechanism.     

TiB2对放电等离子烧结法合成Ti3AlC2/TiB2复合材料性能和结构的影响

放电等离子烧结合成了Ti_3AlC_2/TiB_2复合材料,对其进行了密度、硬度、相含量、断裂韧性和弯曲强度以及微观结构的测试,比较系统地研究了TiB_2对Ti_3AlC_2/TiB_2复合材料性能和结构的影响。实验结果表明:在Ti_3AlC_2中添加适量的TiB_2,可以在断裂韧性略有降低的情况下,得到高硬度和高弯曲强度的致密的Ti_3AlC_2/TiB_2复合材料。     

金属Al-Si结合Al2O3-C滑板的性能和使用

自主研制开发了节能型低碳金属Al-Si结合Al2O3-C滑板,其工艺特点是低温烧成,产品特性是低碳,与常用的Al2O3-C和Al2O3-ZrO2-C滑板相比,具有较高的热态强度,较好的抗热震性和抗氧化性。经大中型钢包的批量使用表明,其连续使用次数是高温烧成Al2O3-C滑板的两倍,与Al2O3-ZrO2-C滑板相当,用后滑板扩孔均匀,拉毛较少,裂纹微细。经残砖分析,认为金属Al-Si结合Al2O3-C滑板使用时的损毁过程可能是:表面工作层的非氧化物首先被氧化,导致结构疏松,强度降低,在铸孔处由高温钢水冲刷引起铸孔扩大,在滑动面处因机械摩擦造成滑动面拉毛。     

镍-钨-碳化硅非晶复合刷镀工艺的研究

为进一步提高非晶态镍－钨合金镀层的硬度,耐磨和耐蚀性能,在镍－钨刷镀液中加入适量碳化硅微粒,共沉积制得含碳化硅26．0－21．3％（质量分数）的非晶态镍－钨－碳化硅复合镀层。利用X射线衍射技术分析了所得镍－钨－碳化硅镀层的结构,研究了镀层中碳化硅含量,热处理温度复合镀层硬度,耐磨性和抗高温氧化性的影响。结果表明：碳化硅的弥散强化作用和热处理能显著提高复合镀层的硬度,耐磨性和抗高温氧化性。     

晶须含量对Al2O3＋SiCw陶瓷刀具切削加工时磨损和破损的影响

晶须含量不同将影响到Ａｌ＿２Ｏ＿３３＋ＳｉＣ＿ｗ陶瓷刀具材料的力学性能，由此将进一步影响到该刀具材料切削加工时的抗磨损和破损性能。本文试验了不同晶须含量的Ａｌ＿２Ｏ＿３＋ＳｉＣ＿ｗ陶瓷刀具在连续切削时的抗磨损性能和断续切削时的抗破损性能。结果表明，晶须含量对该刀具材料的磨损和破损有很大的影响。因此在实际应用中应根据刀具损坏方式的不同分别选用不同晶须含量的Ａｌ＿２Ｏ＿３＋ＳｉＣ＿ｗ刀具材料，以充分发挥该刀具材料的增韧补强效果。     

MoSi2–再结晶SiC复合材料的高温抗氧化性能及氧化机理

在SiC粉中添加MoSi2粉,采用模压成型、无压烧成方法制备MoSi2–再结晶SiC(RSiC)复合材料。利用扫描电子显微镜、X射线衍射和等温氧化法研究复合材料的高温抗氧化性能及氧化机理。结果表明,所得复合材料中SiC为6H型,部分MoSi2转变为六方结构Mo4.8Si3C0.6,添加MoSi2前后样品的氧化产物均为方石英,样品表面生成的氧化膜形貌相似。氧化过程中样品质量变化与时间关系遵循抛物线规律,随MoSi2添加量增加,复合材料的抗氧化性能显著提高,其中,添加20%(质量分数)MoSi2所得复合材料在1500℃循环氧化100h后质量增加量仅为未添加MoSi2样品的37%。当MoSi2添加量为10%时,复合材料的抗氧化性能随样品烧成温度的升高先提高后降低,2 300℃烧成所得材料有较好的高温抗氧化性能,其氧化速率常数为0.99mg2/(cm4.h)。在氧化初始阶段,Mo4.8Si3C0.6和MoSi2首先发生氧化反应,随氧化时间增加,Mo4.8Si3C0.6和MoSi2消耗殆尽,此后的氧化则主要为Mo5Si3和SiC的氧化。SiO2膜的致密性和膜厚度与膜中Mo5Si3的含量有关。     

Performance and wear mechanism of spark plasma sintered WC-Based ultrafine cemented carbides tools in dry turning of Ti–6Al–4V

Cutting performance and failure mechanisms of spark plasma sintered (SPS) ultrafine cemented carbides in dry turning Ti–6Al–4V were studied. The tools of UYG8 (WC-8wt%Co) and UYG8V2B10 (WC-8wt%Co-0.2 wt%VC-1.0 wt%cBN) exhibited higher lifetime and better processing quality than the commercial YG8 cemented carbide tool. The cutting distance of UYG-8 and UYG8V2B10 tools are 1.8 and 1.6 times longer than that of YG8, respectively. Cutting-edge breakage was found as the main failure forms of the SPS cemented carbide tools containing low Co content (≤6 wt%), whereas the SPS cemented carbide tools containing high Co content (≥8 wt%) exhibited flank and rake wear as main failure forms caused by abrasion, adhesion, diffusion, and oxidation. UYG8V2B10 tool wear mechanism was affected by cutting speed and depth. Wear mechanisms of UYG8V2B10 tool are mainly adhesive wear and oxidative wear at low cutting speed, but follow adhesive wear and diffusive wear at higher cutting speed. Moreover, with increasing cutting depth, tool failure forms are mainly breakage and chipping, largely induced by high cutting temperature and severe cutting vibration.     

原位合成碳化硅-硼化钛复相陶瓷的高温摩擦性能及其磨损机理

以SiC为基体,用TiC和B4C为原料反应生成TiB2,原位合成了SiC-TiB2复相陶瓷.通过测试SiC和SiC-TiB2的高温摩擦系数和比磨损率与温度、外加载荷的关系,研究了SiC-TiB2复相陶瓷的高温摩擦学性能.在空气中,外加载荷为0.2 MPa,摩擦速度为0.3 m/s时,SiC-TiB2复相陶瓷自对偶(SiC-TiB2/SiC-TiB2)高温摩擦呈现较好的高温自润滑性能.温度对SiC-TiB2/SiC-TiB2摩擦系数和比磨损率的影响与载荷有关.载荷为0.4 MPa时,比磨损率最大.用X射线衍射测试了SiC-TiB2/SiC-TiB2磨屑的组成,用扫描电子镜观察了SiC-TiB2/SiC-TiB2磨损断面,发现高温摩擦氧化是TiB2-SiC/SiC-TiB2磨损的主要机理.磨损断面包含摩擦氧化层、过渡层和基体亚表面3层,氧化层和过渡层接触紧密.磨屑具有典型包裹结构,其主要氧化物是无定形氧化硅.平滑的氧化层改进了摩擦表面的塑变性能,缓冲了摩擦应力,减小了高温比磨损率.